Handbook p10 astronomy

Agastya International Foundation

Astronomy Handbook P11

“Science is a way of thinking, much more than it is a body of knowledge.�

-Carl Sagan, (1934-1996)

1

HANDBOOK P11 ASTRONOMY OVERVIEW OF HANDBOOK

ABL

Concept

No. of Activities

ABL 1

Introduction To The Universe

2

40

ABL 2

Introduction To Earth

5

75

ABL 3

Introduction To Moon And Eclipse

3

60

ABL 4

Constellations

2

60

TOTAL

Time (Min)

245 min

ABL WITH REFERENCE TO STANDARD S.No 1 2 3 4

Standard 6 and 7 6,7 and 8 6, 7 and 8 8

Relevant ABL ABL 1 ABL 2 ABL 3 ABL 4

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Page No.

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LIST OF FIGURES, CHARTS AND WORKSHEETS S.No Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 Fig 6 Fig 7 Fig 8 Fig 9 Fig 10 Fig 11 Fig 12 Fig 13 Fig 14 Fig 15 Fig 16 Fig 17 Fig 18 Fig 19 Fig 20 Fig 21 Fig 22 Fig 23 Fig 24 Fig 25 Fig 26 Chart 1 Chart 2 Chart 3

Name Haley’s Comet Kuiper Belt Rotation of the Earth Revolution of the Earth around the Sun Rotation and Revolution Period of the Earth How things will be seen if the Earth was flat Visibility if Earth is spherical Bulging of Earth model Day and Night model Day and Night on Earth Occurrence of Seasons Formation of seasons Rotation and Revolution period of the Moon Same face of moon model Same face of moon model 2 Phases of the moon Phases of the moon 2 Phases of the Moon- New moon Phases of the Moon- Waxing Crescent Phases of the Moon- First Quarter Phases of the Moon- Waxing Gibbous Phases of the Moon- Full Moon Phases of the Moon- Waning Gibbous Phases of the Moon- Last Quarter Phases of the Moon- Waning Crescent Model representing solar eclipse India World Solar System

Page Number 19 20 25 25 27 32 32 34 38 39 41 42 53 54 57 57 58 59 60 60 61 61 62 62 63 64 7 7 8

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Chart 4 Chart 5 Chart 6 Chart 7 Chart 8 Chart 9 Chart 10 Chart 11 Chart 12 Chart 13 Chart 14 Chart 15 Chart 16 Chart 17 Chart 18 Chart 19 Chart 20

Milky Way Galaxy The Local Group The Local Group 2 Virgo Super Cluster Virgo Super Cluster 2 The Observable Universe Our Solar System Our Solar System 2 Pluto’s Orbit Moon as seen from the Earth Far side of the moon Same face of the moon faces the earth Faces of the Moon that are seen from the Earth Difference between eclipse and phases of the moon Solar Eclipse Lunar Eclipse Constellations

8 10 10 11 11 12 14 17 18 50 50 52 52 59 65 66 75

Note to Instructor: All the figures in this handbook are for the Instructor’s reference only. The Charts need to be printed and shown to the learners during the course of the activity. Worksheets need to be printed out in advance for the learners. The number of worksheets required is mentioned in the Material List.

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ABL 1: INTRODUCTION TO THE UNIVERSE

ABL

Learning Objective

Key Message   

1.1

Our Cosmic Address

 

1.2

Introduction system

of

Time

Our planet Earth is one of the 8 20 min planets which orbit the sun.

The Sun and planets along with other celestial objects form the solar system.

There are millions of solar systems in a galaxy.

The galaxy, that our solar system belongs to, is called the Milky Way. A very large number of galaxies make up our observable universe.

What lies beyond our observable universe is still a mystery.

Our solar system consists of 20 min 1 Star  Sun 8 planets  Mercury  Venus  Earth  Mars  Jupiter  Saturn solar  Uranus  Neptune Satellites both natural (Moon) and artificial (man-made) Asteroid belt Dwarf Planets Comets

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ABL 1.1

Time: 20 min

LEARNING OBJECTIVE: Our Cosmic Address.

ADVANCE PREPARATION Material List S. No. 1 2 3

Materials TV Chart 1 to Chart 9 Chart 1 and Chart 2 or India map and world map

Quantity 1 Each 1 per class Each 1 per student

Things to do This activity includes playing a video for the students. So download the videos from the link given below and play it on the TV. Take appropriate permission to use the TV. http://www.youtube.com/watch?v=0fKBhvDjuy0 http://www.youtube.com/watch?v=qxXf7AJZ73A Take printout of the Chart 1 to Chart 9.

Note to Instructor Watch both the videos and understand the concept. Both the videos explain the same concept. The instructor can choose any one of the videos for the class. The video is in English so give a brief explanation about the video in the beginning.

The instructor might find the format of this activity a bit different from the usual ABL format. But the rest of the activities follow the general ABL format.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Not Applicable Procedure Use the printout to explain the concept first. You can show one picture after another in an order from Chart 1 to Chart 9. At the end of the activity play the video.

Start this activity by asking the students a series of leading question.

UNDERSTANDING THE ACTIVITY Leading questions 1. Which district does their school belong to?

2. Which state does their district belong to?

3. Which country does their state belong to?

4. Which continent does their country belong to?

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5. Where is this continent? The answer would be the planet Earth.

Discussion and Explanation EARTH Most students will answer all of the leading questions. Use Chart 1 to show the district (if possible), state and our country and Chart 2to show the world. Alternatively the instructor can use the Earth globe to do the same.

Give Chart 1 and Chart 2 or the maps one per each student and ask them to mark their district (if possible), the state they belong to and our country. You can also ask the students to spot the 7 continents and the few oceans and seas. This is just to give them an idea of the geography of earth.

Chart 1 India

Chart 2 World

SOLAR SYSTEM Now ask the students where does the Earth belong to? Most students answer would be solar system.

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Chart 3 SOLAR SYSTEM [Note the next activity is about the solar system. So the instructor can now teach activity 1.2 (a detailed description of the solar system is given there) and then continue with the rest of this activity] Chart 3 shows the solar system which is enclosed by the Oort Cloud. Show this to the students.

MILKY WAY GALAXY Now ask the students where does the solar system belong to? Most students will not know the answer.

Tell them our Solar System belongs to a galaxy called the Milky Way. Show them Chart4 which contains our Milky Way galaxy. The circle in the picture shows the position of our solar system in the Milky Way galaxy.

Chart.4 Milky Way Galaxy What is a galaxy?

A galaxy consists of million or billion number of stars.

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Our galaxy is called the Milky Way because the disk of the galaxy runs across the sky as a band of glowing light, like spilled milk.

Can we see the band of stars in the galaxy with our naked eye?

Yes we can. Refer to the take home activity 1 after completing the ABL. What is the structure of Milky Way galaxy?

Milky Way is a barred spiral galaxy as shown in the fig 1.1.4 measuring about 120,000 light-years across and about 1,000 light-years thick. It has 2 spiral arms: they are called Scutum–Centaurus and Carina– Sagittarius. Our Sun is located in the Orion Arm, a region of space in between the two major arms of the Milky Way at about 27,000 light years from the galaxy’s centre. There are between 100 and 400 billion stars in the Milky Way. Recollect activity 1.2 where we learnt our solar system consist of a star – our sun, 8 planets including Earth, many dwarf planets which includes Pluto , a belt of asteroids and many comets orbiting our sun. Likewise most of the stars in a galaxy have their own solar system.

Thus there are hundreds of billions of planets in the Milky Way, and at least 17 billion of those are of the size and mass of the Earth. But we do not know if there are any intelligent lives in those planets.

If all we can see is a band of stars in the night sky from the Earth, then how did the astronomers get the overall structure of the galaxy?

It’s very difficult to figure out what the Milky Way galaxy looks like exactly, because our Earth along with the solar system is embedded inside it. If you’d never been out of your house, you wouldn’t know what it looked like from outside. But you’d get a sense by looking at other houses in your neighborhood. This is how exactly the astronomers decided on the structure of our galaxy. So the fig 1.1.4 is just an artistic impression of our galaxy.

Does that mean there are more galaxies?

Yes. There are many galaxies and looking at their structure the astronomers came to a conclusion about the structure of our galaxies. Our nearest neighboring galaxy is Andromeda. It is about 2.5 million light years from Earth and twice as bigger than our galaxy.

THE LOCAL GROUP Our galaxy along with Andromeda galaxy and a few other galaxies is called the local group.

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Chart 5 The Local Group

Chart 5 shows our Milky Way galaxy and the Andromeda galaxy along with the Local group of galaxies. The Local group consists of about 31 galaxies including our Milky Way and Andromeda galaxies.

These 31 galaxies are shown in theChart6. Show both the Charts 5 and 6 to the students. The instructor can also ask the students to spot few galaxies from Chart6.

The next obvious question is where the local group belongs to.

Chart.6 Local Group 2 THE VIRGO SUPERCLUSTER The local group belongs to a cluster of galaxies called the Virgo Super Cluster.

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Chart7 Virgo Super Cluster We can’t even spot our own galaxy in the Chart7. It is just one of thousands in the Virgo Super Cluster. On this scale every dot on the Chart7 is a galaxy. Each galaxy consists of billions of stars and countless planets.

Chart 8 – The Virgo Super Cluster2 THE OBSERVABLE UNIVERSE The entire Virgo Super Cluster itself forms but a tiny part of our observable universe.

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Chart 9 – The Observable Universe

The entire observable universe consists of a network of hundred billion galaxies. What lies beyond this observable universe is a mystery.

What is an observable universe?

It is the part of the universe we know that exists. The Chart 9is also an artistic impression of how the universe could look.

Show this Chart 9to the students.

OUR COSMIC ADDRESS Our cosmic address is our address in the universe.

EARTH SOLAR SYSTEM MILKY WAY LOCAL GROUP VIRGO SUPER CLUSTER OBSERVABLE UNIVERSE Imagine how small we are in the entirety of the universe.

At the end of the activity show the students the video.

KEY MESSAGES    

Our planet Earth is one of the 8 planets which orbit the sun.

The Sun and planets along with other celestial objects form the solar system.

There are millions of solar systems in a galaxy.

The galaxy, that our solar system belongs to, is called the Milky Way.

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

A very large number of galaxies make up our observable universe. What lies beyond our observable universe is still a mystery.

INTERESTING INFORMATION  Light year is a unit of length used in astronomy. One light year is the distance travelled by light in one year. Its symbol is ly.

1 ly =3,00,000 (km/s)x 365 (days) x 24 (hours) x 60 (min) x 60 (sec)= 9.4607×1015 m  Sun takes 225 million years (=1 cosmic year) to complete 1 revolution around our galaxy centre.  Similarly every star in the galaxy rotates and revolves around with in the galaxy.  Scientists have found that our universe is expanding as every galaxy in the observable universe is accelerating from each other.

VOCABULARY Light year – It is a unit of length used in astronomy. Its symbol is ly. 1 ly = 9.4607×10 15 m Galaxy– It is one of the units into which our universe is divided and it consists of millions or billions of stars.

Solar system – A star with other celestial object orbiting it Milky Way Galaxy – It is the galaxy our solar system belongs to. It is given the name Milky Way because the disk of the galaxy runs across the sky as a band of glowing light, like spilled milk.

Cluster – Small group Cluster of stars or galaxy – Small group of stars or galaxies which are close together.

WEB RESOURCES 

Pictures are taken from Google image and Cosmos – a space time odyssey.

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ABL 1.2

Time: 20 min

LEARNING OBJECTIVE: Introduction to our Solar System ADVANCE PREPARATION Material List Take print out of Chart 10, 11, and 12 Things to do Not Applicable.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity This is a continuation of activity 1.1 Procedure Use the Chart 10 to explain the Solar System starting from the Sun to the Comets. While explaining about planets start form the one closest to the Sun, i.e., Mercury and end at Neptune

Chart 10 Our Solar System1

1

https://www.google.co.in/search?q=solar+system+figures&newwindow

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UNDERSTANDING THE ACTIVITY Leading questions 1. What does our Solar system consist of?

2. Is our Sun a star?

3. How many planets orbit our Sun? 4. What is the position of Earth with respect to the Sun? 5. Are all the planets of the same size?

6. Do any of the planets cross the path of another planet?

7. What is an asteroid?

8. What is a comet?

Discussion and Explanation A Solar system consists of a Sun, planets, natural satellites (moons), dwarf planets, asteroids and comets.

SUN The sun is at the center of our solar system and makes up 99.8% of the mass of the entire solar system. All the planets, moons, dwarfs planets, asteroids and comets orbit the sun.

Just like the stars in the night sky our sun is also a star almost perfectly spherical.

A star is a gaseous celestial object held together by its own gravity which radiates electromagnetic waves.

In other words, a star is a huge sphere of very hot, glowing gas which produce their own light and energy by a process called nuclear fusion. Fusion happens when lighter elements are forced to become heavier elements. When this happens, a tremendous amount of energy is generated causing the star to heat up and shine.

Stars come in a variety of sizes and colors. Our Sun is an average sized yellowish star. Stars which are smaller than our Sun are reddish and larger stars are blue.

Without the sun's energy there would be no life on Earth.

PLANETS Planets are solid celestial objects which orbit the Sun. There are eight planets in our solar system, namely,  Mercury  Venus  Earth  Mars  Jupiter  Saturn  Uranus  Neptune Mercury, Venus, Earth and Mars are relatively small, composed mostly of rock, and have few or no moons.

Earth is the third planet from the sun in our solar system.

Jupiter, Saturn, Uranus and Neptune are mostly huge, mostly gaseous, ringed, and have many moons.

Each planet has a defined path called orbit and no planet's orbit intersects the others. Because of the mean distance of the sun and the planet being different, each planet takes different time to revolve around the Sun. The Earth takes 365 days to complete 1 revolution.

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To remember the sequence of the planets from the Sun, we can use the phrase "My Very Enthusiastic Mother Just Served Us Noodles" My - Mercury Very - Venus Enthusiastic - Earth Mother - Mars Just - Jupiter Served -Saturn Us - Uranus Noodles - Neptune MOONS The natural satellites, or moons as these are also called, are solid celestial objects that revolve around a planet. Unlike the sun, it is non-luminous. In other words, it does not produce its own light but just reflects the light it receives from the sun.

In our solar system, Mercury and Venus have no moos, Earth has one, Mars has two, and the other four planets, i.e., Jupiter, Saturn, Uranus and Neptune, have many each. These moons revolve around their respective planet.

An artificial satellite refers to a man-made satellite like Aryabhata, Bhaskara, Apollo which were made of humans and intentionally put into orbit (around earth) to study these celestial objects.

The detailed description of the sun and planets are given in the end of the ABL as Table 1.

ASTEROIDS During the formation of the solar system a planet which was supposed to form between the orbits of planets Mars and Jupiter could have broken up into small solid fragments of rocks. These essential chunks of rock that measure in size from a few feet to several miles in diameter are called as Asteroids. They are many numbers of asteroids and each and every one of them orbits our sun forming a belt of asteroids known as asteroid belt in our solar system. This asteroid belt divides the planets into inner planets and outer planets.

SOLAR SYSTEM INNER PLANET OUTER PLANET Mercury

Jupiter

Venus

Saturn

Earth

Uranus

Mars

Neptune

Chart 11shows the relative size of the planets with the asteroid belt and Kuiper belt.

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Chart 11: Our solar system2 DWARF PLANETS Dwarf planets are round and orbit the Sun just like the eight major planets. But unlike planets, dwarf planets are not able to clear their orbital path so there are no similar objects at roughly the same distance from the Sun. A dwarf planet is much smaller than a planet (smaller even than Earth's moon), but it is not a moon. Pluto is the best known of the dwarf planets. It is about 5.9 billion km away from the sun.

Chart 12 Pluto’s Orbit3 2

https://www.google.co.in/search?q=solar+system+figures&newwindow

3

https://www.google.co.in/search?q=solar+system+figures&newwindow

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Earlier, Pluto was included as one of the planets but new scientific information revealed that it is not a planet but a 'Dwarf Planet'. One of the main reasons is its orbit. It’s exceptionally elliptical and crosses Neptune's orbit as shown in Chart 12.

There are 5 officially recognized dwarf planets in our solar system, namely,  Ceres  Pluto  Haumea  Makemake  Eris With the exception of Ceres, which is located in the asteroid belt, all the other dwarf planets are found in the Kuiper Belt, a region of icy objects beyond the orbit of Neptune.

These Dwarf planets orbit our sun. Days and years vary on dwarf planets.

Dwarf planets are solid rocky and/or icy bodies. The amount of rock vs. ice depends on their location in the solar system. Many, but not all dwarf planets have moons.

There are no known rings around dwarf planets.

They cannot support life.

COMETS Comets are big chunks of frozen gases, rock and dust that orbit the sun. When a comet's orbit brings it close to the sun, it heats up and spews dust and gases into a giant glowing head called coma. The comet may be hundreds of thousands of kilometers in diameter. The dust and gases form a tail that stretches away from the sun for millions of kilometers.

Fig 1 Haley’s Comet Short-period comets (comets that orbit the sun in less than 200 years) reside in the icy region known as the Kuiper Belt beyond the orbit of Neptune.

Long-period comets (comets with long, unpredictable orbits) originate in the far-off reaches of the Oort Cloud, which is five thousand to 100 thousand AUs from the sun.

Days on comets vary. One day on comet Halley varies between 2.2 to 7.4 Earth days and one year is 76 Earth years.

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Comets do not have moons. Comets do not have rings.

Comets may not be able to support life themselves, but they may have brought water and organic compounds -- the building blocks of life -- through collisions with Earth and other bodies in our solar system.

KUIPERS BELT AND OORT CLOUD The Kuiper Belt and the Oort Cloud are regions of space that surround our sun.

Kuiper Belt Oort Cloud It is a doughnut-shaped ring, extending just The Oort Cloud is a spherical shell, beyond the orbit of Neptune from about occupying space at a distance between five 30 to 55 AU.Short-period comets (which thousand and 100 thousand AU. Longtake less than 200 years to orbit the Sun) period comets (which take more than 200 originate in the Kuiper Belt. There may be years to orbit the sun) come from the Oort hundreds of thousands of icy bodies larger Cloud. The Oort Cloud may contain more than 100 km and an estimated trillion or than a trillion icy bodies. more comets within the Kuiper Belt.

Several dwarf planets in the Kuiper Belt have tiny moons.

There are no known rings around worlds in either region of space. Neither region of space is capable of supporting life as we know it.

Fig 2 Kuiper Belt Chart 3 in activity 1.1 shows the Oort Cloud.

KEY MESSAGES Our solar system consists of 1 Star  Sun 8 planets orbiting the sun, namely  Mercury  Venus  Earth  Mars  Jupiter  Saturn Agastya International Foundation. For Internal Circulation only.

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 Uranus  Neptune Satellites both natural (Moon) and artificial (man-made) Asteroid belt Comets

TRY IT YOURSELF Make a model of the Solar system using clay and paste them on a chart paper. Draw the orbits and the direction of the revolution around the Sun. The sizes of the planets should convey the relative size of the actual planets. The colours of the planets are defined, so use the correct colour of clay.

Draw the sun and the orbits of all eight planets on the school playground. Each Student should represent a planet and walk their respective orbit around the sun depicting the planet.

INTERESTING INFORMATION  The surface of Mercury is very similar to the surface of our Moon; it is a grey planet covered with craters. The color of the surface comes from the iron and other heavy compounds that comprise the rocky surface of the planet.  Venus appears to be yellowish in color, which is caused by sulfuric acid in the thick atmosphere of the planet.  The Earth, as seen from space, is blue with patches of white, green, and brown.  Mars is famous for its reddish color. The red color results from rust in the rocks on the surface, which are visible because there is almost no cloud coverage on Mars.  Jupiter is composed of various gases including hydrogen and helium. Like Venus, Jupiter has sulfur in its environment, which gives it a dirty yellowish hue. There are also spots of other colors on the planet as a result of the violent storms that occur there. The Great Red Spot is the most famous storm on the planet.  Saturn is a gas planet with bands of orange and white. Ammonia forms the clouds of white, while ammonia hydrosulfide creates the orange clouds. In photographs, this planet is often colored more vibrantly with yellows and reds.  Uranus is light bluish-green because there is a large amount of methane gas in the planet.  Neptune is also blue because there is a significant amount of methane in the planet. Neptune is a slightly darker blue than Uranus because it is farther from the Sun.  Sun also rotates about its axis and revolves around the center of the Milky Way galaxy. Its period of rotation is different in equator and the pole regions. It takes 225 million years (=1 cosmic year) to complete 1 revolution around the Milky Way galaxy. But we say sun is stationary in reference to our solar system.  Many people think that moons are smaller than planets. This, however, is not true. There are several moons in the Solar System which are larger than the planet Mercury. There are moons with volcanoes, atmospheres, and even quite possibly liquid water oceans. The difference between moon and planet depends around which celestial object they revolve. If the celestial object revolves the Sun it is called a Planet, however, if it revolves another world instead of the Sun then it is called a moon.

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 The Kuiper Belt and the Oort Cloud are named after the astronomers who predicted their existence during the 1950s: Gerard Kuiper and Jan Oort.  Light travels at the speed of 3, 00,000 Km/sec. Sunlight takes about 8 minutes 17 seconds to travel the average distance from the surface of the Sun to the Earth.  1 Astronomical Unit , AU = 1.50 × 1011 m

LEARNING CHECK 1. Make Placards naming the planets, the Sun, the moons and asteroids. Divide the students into three groups. Give the placards to one group. The second group has to place them as they appear in the solar system. The third group has to explain about the Sun, the planets, the moons, and the asteroids.

VOCABULARY Celestial Object- A natural object which is located outside of Earth's atmosphere, such as the Moon, the Sun, an asteroid, planet, or star.

Sun– It is a star of our solar system.

Star – Gaseous celestial object held together by its own gravity. In other words, a star is a huge, bright ball of burning gas that is held together by gravity.

Planet- A Celestial body moving in an elliptical orbit round a star Moon – A Celestial body moving in an elliptical orbit around a moon.

Asteroid– Asteroids are small solar system bodies that orbit the Sun. Made of rock and metal, they can also contain organic compounds.

Asteroid belt- The asteroid belt lies between the orbits of Mars and Jupiter in the Solar System. It is home to a large amount of irregular shaped asteroids that range in size from dust through to the dwarf planet Ceres.

Dwarf Planets- A Celestial object similar to a planet but very small even smaller than a moon but not a moon.

Comet- A comet is a relatively small solar system body that orbits the sun. When close enough to the Sun they display a visible coma (a fuzzy outline) and sometimes a tail.

Kuiper Belt- It is a doughnut-shaped ring, extending just beyond the orbit of Neptune from about 30 to 55 AU. Oort Cloud- The Oort Cloud is a spherical shell, occupying space at a distance between five thousand and 100 thousand AU.

WEB RESOURCES   

Comparison of distance from the sun: http://www.exploratorium.edu/ronh/solar_system/ http://www.universetoday.com http://www.kidsastronomy.com/solar_system.htm

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ABL 2: INTRODUCTION TO EARTH Time Activity

Learning Objective

Key Message

To understand Rotation and Revolution of planets



To recognize the shape of the Earth



2.3

To learn how day and night occur



2.4

To learn how seasons occur

2.1

2.2



 2.5

Understanding retrograde motion

Every planet rotates about its axis and revolves around its sun.

15 min

The shape of earth is like a sphere, but a little flattened at the poles.

15 min

Days and nights occur due to the rotation of the Earth about its axis.

15 min

Seasons occur due to the tilt of the earth's axis and the Earth's revolution around the Sun It is the apparent motion of an object to move in a direction opposite to that of other object, as seen from a certain reference point Total Time

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15 min

15 min

75 min

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ABL 2.1

Time: 15 min

LEARNING OBJECTIVE: (a) Rotation and Revolution of Planets ADVANCE PREPARATION Material List Not Applicable Things to do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity Not Applicable Procedure Ask two students to step forward. Let one of them be stationary and the other go around the stationary student in counterclockwise direction.

Compare these students to the Sun and the Earth.

Later ask the moving student to spin in counter clockwise direction as he/she goes around the stationary person.

UNDERSTANDING THE ACTIVITY Leading questions 1. What is spinning about one’s own axis called?

2. What is going around a stationary object called?

3. If you compare the students to the Earth and the Sun, who is the Sun and who is the Earth?

4. So what can you infer?

5. Finally what can you say about the movement of the Earth?

Discussion and Explanation When any object spins (or circles) 3600 about its own axis it is called as rotation. Similarly, the Earth spinning (or circling) 3600 about its axis is called as Rotation. It takes 24 hours (1 day) for the Earth to complete one rotation.

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Fig. 3: Rotation of the Earth4

When an object goes (or circles) 3600 around another object, it is said to be revolving around that object. Here the stationary student is the Sun and the student going around the stationary student is the Earth. So we say the Earth revolves around the Sun. So, the Earth rotates around its axis and revolves around the Sun at the same time. It takes the Earth 365.249 days to complete one revolution. So, every four years, we have one day added to our calendar. We call this a leap year and it has 366 days.

Fig. 4: Revolution of the Earth around the Sun 5

4

http://www.thunderboltkids.co.za/Grade6/04-earth-and-beyond/images/gd-0045.png

5

http://www.kidport.com/reflib/science/space/Earth.htm

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The rotation and revolution applies to every planet in the universe. Our Solar System has eight planets rotating about their respective axis and at the same time revolving around our Sun. Their rotation and revolution periods are different compared to Earth. One reason for the difference is because of the distance of the planet from the sun. The rotation and revolution periods of the 8 planets are given in table 1 at the end of the ABL.

KEY MESSAGE  

Every planet rotates about its axis.

Every planet revolves around its Sun.

VOCABULARY Rotation: An object spinning (or circling) 360 0about its own axis.

Revolution: An object circling 3600around another object.

Day: One complete Earth Rotation.

Year: One complete Earth Revolution around Sun.

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ABL 2.1 LEARNING OBJECTIVE: (b) Rotation and Revolution of Earth ADVANCE PREPARATION Material List Season Model Things to do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity This activity is the demonstration for the previous activity 2.1 (a) using Season Model.

Note to Instructor Ask the students to compare the model to the activity 2.1 (a).Ask the student to explain the model.

This gives the instructor a chance to analyze how far the students have understood the concept.

Procedure Operate the model by turning the handle slowly in counter clockwise direction and observe the movements of the earth around the sun.

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Fig 5 Rotation and Revolution Period of Earth

UNDERSTANDING THE ACTIVITY Leading questions 1.

2.

3.

4.

Which is the sun and which is the earth?

What can you say about the movement of the Earth?

Which movement is rotation?

Which movement is revolution?

Discussion and Explanation The light bulb represents the sun and the blue globe represents the earth  The Earth spins 3600 about its own axis in counter clockwise direction.  This is known as Rotation It takes 24 hours (1 day) for the Earth to complete one rotation.  Also the Earth moves 3600 in its orbit around the sun. This is called as Revolution.  Again its revolution is also in counter clockwise direction.

It takes 365.249days (1 year) for the earth to complete one revolution.

KEY MESSAGE 

Earth rotates about its axis and revolves around sun. The direction of rotation and revolution is counter clockwise.

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INTERESTING INFORMATION Universal Law of Gravitation6: Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. The force is along the line joining the centers of two objects.

where:  F is the force between the masses,  G is the gravitational constant,  m1 is the mass of the first object,  m2 is the mass of the second object, and  r is the distance between the centers of the masses.

Kepler's Laws of Planetary Motion7 To understand Kepler's laws, it is important to understand a few properties of ellipses. We will take two of them and simplify them to make a better understanding.

1. For an ellipse there are two points called foci (singular: focus) such that the sum of the distances to the foci from any point on the ellipse is a constant. In terms of the diagram shown to the left, with "x" marking the location of the foci, we have the equation a + b = constant that defines the ellipse in terms of the distances a and b.

2. The long axis of the ellipse is called the major axis, while the short axis is called the minor axis. Half of the major axis is termed a semimajor axis. Thus, by the "radius" of a planet's orbit one usually means the length of the semimajor axis.

6

http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitation

7

http://csep10.phys.utk.edu/astr161/lect/history/kepler.html

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Kepler's First Law: The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.

The Sun is not at the center of the ellipse, but is instead at one focus (generally there is nothing at the other focus of the ellipse). The planet then follows the ellipse in its orbit, which means that the Earth-Sun distance is constantly changing as the planet goes around its orbit.

Kepler's Second Law: The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse.

The line joining the Sun and planet sweeps out equal areas in equal times, so the planet moves faster when it is nearer the Sun. Thus, a planet executes elliptical motion with constantly changing angular speed that increases on approaching the Sun and decreases while receding from the Sun as it moves about in its orbit.

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Kepler's Third Law: The ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semimajor axes:

where: P1–Period of revolution of Planet 1 P2 – Period revolution of Planet 2 R1 - Length of semimajor axis of Planet 1 R2 - Length of semimajor axis of Planet 2 Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. Thus, we find that Mercury, the innermost planet, takes only 88 days to orbit the Sun but the outermost dwarf planet (Pluto) requires 248 years to do the same.

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30 Time: 15 min

ABL 2.2 LEARNING OBJECTIVE: (a) Oblate shape of the Earth ADVANCE PREPARATION Material List: S. No.

Materials

Quantity

1

Cardboard

2

2

Football or a large spherical object

2

3

6" long pencil

4

4

A 2" doll or human figure

4

Things to do This is a group activity. Each person in the group should be encouraged to participate.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Not Applicable Procedure Divide the class into 4 groups. Give one cardboard, one pencil and one doll to Groups 1 and 2. Ask them to explain why the earth's shape cannot be flat like a card board.

Give one football, one pencil and one doll to Groups 3 and 4. Ask them to explain if it is possible to have the shape of the earth like a football.

Give each group 5 minutes to discuss and present their reasons. This activity will be done by each group simultaneously so they will be in different corners of the classroom. The teacher will have to go to each group and ask questions to lead them to their answers.

Note: Do not squash any idea as stupid or laugh at any explanation. The students are trying to use their knowledge and tiring to horn their presentation skills. The teacher and other students need to be sensitive to the feelings of the students presenting the ideas.

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UNDERSTANDING THE ACTIVITY Leading questions 1. How far can the doll see when placed on the cardboard and the football?

2. If there is no obstruction, why cannot we see hundreds of kilometers away?

3. If we are at a higher place, like a mountain, can we see further?

4. What will happen if the surface of the earth was flat?

Discussion and Explanation Let us assume that the shape of the Earth is like a cardboard. Place the doll on the cardboard. Let us assume that the doll is us on the Earth. Place the pencil at any place. Can we see the pencil?

Yes, we can. It can be kept at any distance and it can be seen. But in real life, even a tall building cannot be seen at a large distance. Now, suppose you keep walking on this flat earth (show it with the doll walking to the edge of the cardboard), what should happen if you come to the end of the Earth? You will fall off! But this does not happen in real life!

Fig.6: How things will be seen if the Earth was flat

Now, consider the Earth as being spherical like a football. Place the pencil and the doll on it. Will the doll see the pencil at all times. No. When the curve of the football comes in between the doll and the pencil, it will not be able to see the pencil. Now let us walk the doll all over the football.

Will it fall off? No. Because there is always a place for it to walk further!

Fig. 7 Visibility if Earth is spherical

a. When the curvature of the Earth does not hinder the line of sight

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b. When the curvature of the Earth hinders the line of sight

So, we can say that the shape of the Earth is spherical.

If you fly in an aeroplane straight in any direction maintaining the same height from the ground, after several hours, you will come back to the same place. T means you have made a circular path.

Earth is therefore round or circle in all directions, or a sphere.

But in reality, the Earth is not a perfect sphere. It is like an orange, a little flat on the top and bottom, i.e., at the poles, and bulging at the equator. This shape is called oblate spheroid. The surface of the Earth was flat; there would be an end after which we would fall off.

KEY MESSAGE 

The shape of earth is like a sphere, but a little flattened at the poles.

VOCABULARY Oblate Spheroid: The true shape of the Earth is called an Oblate Spheroid. The term 'Oblate' refers to its slightly oblong appearance. The term 'Spheroid' means that it is almost a sphere, but not quite8.

ABL 2.2 8

http://www.regentsprep.org/Regents/earthsci/units/introduction/oblate.cfm Agastya International Foundation. For Internal Circulation only.

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LEARNING OBJECTIVE: (b) The shape of the Earth ADVANCE PREPARATION Material List: Working Model Things to do Not Applicable Safety Precautions Not Applicable

SESSION Procedure

Fig 8 Bulging of Earth model Operate the model to rotate the strips vertically at suitable speed and observe the change in the shapes of the rings.

UNDERSTANDING THE ACTIVITY Leading questions 1. What happens to the shapes of the rings?

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2. Does it bulge or contracts and in which direction?

3. What force is acting on the strips?

Discussion and Explanation When the model is operated there is a diametric elongation of the strips in the horizontal direction. The centrifugal force acting on the strips exerts a net outward force and causes the strips to bulge. The same applies to the Earth. As the Earth rotates due to centrifugal force there is an increase in diameter in the equatorial region and flattening at the poles. Hence the shape of earth is like a sphere, but a little flattened at the poles. This shape is called oblate spheroid. The same reason applies for other planets.

As the earth rotates about its axis, each part of the earth describes a circular path about the axis. A part of earth of mass m experiences an outward centrifugal force, F = mRđ?œ”2. This force acting at every place tries to pull the earth outwardly. But if we go from the equator to the pole, the radius of the circular path decreases. As a result the outward pull also decreases. Hence the equatorial region experiences a larger pull has maximum elongation. The earth takes the shape of oblate spheroid.

KEY MESSAGE 

The true shape of the Earth and other planets are Oblate Spheroid.

ABL 2.3

Time: 15 min

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35

LEARNING OBJECTIVE: To learn how day and night occur.

ADVANCE PREPARATION Material List: Season Model Things to do Ensure that the room where the activity is to take place can be made into a dark room. This can be done by covering all the windows with dark cloth or paper and closing the doors and putting off all the lights.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect about Earth’s rotation from activity 2.1 Procedure Place the Season model on the table. Explain to the students that the light bulb represents the Sun. Make one of the students find India on the globe. Turn the globe so that the beam of light falls on India. Now slowly rotate the globe from west to east using the handle. Tell the students to observe the sequence of the countries that come into the lighted portion. Also observe what happens to India when the globe rotates.

UNDERSTANDING THE ACTIVITY Leading questions 1. When the light bulb is lit, how much of the globe can you see clearly?

2. When the light from the Sun (light bulb) falls on India, which other countries also get lit?

3. Which countries do you see coming into the bright portion when the globe rotates?

4. Is India always illuminated?

5. When does India come into the bright portion again?

Discussion and Explanation The light from the light bulb illuminates only half the globe. The other half is in darkness. This is because the light from the light bulb does not reach the other side of the globe. This is the same case with the Sun and the Earth. When the light from the Sun falls on the Earth, only half of the Earth gets illuminated since it is facing the sun. Hence it is day time for people living in these Agastya International Foundation. For Internal Circulation only.

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regions. The other half which is not facing the sun is in complete darkness and its night for people in those regions.

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Fig. 9: Day and night model9

We then see when the globe is rotated; some countries go from brighter to the darker side. We have started with India in the bright area. At this time, Pakistan, Bangladesh, the Middle East and some parts of Europe and Africa are also in the bright portion. Thus its day for these countries and night for the rest of the globe. As the globe rotates from west to east, the countries and continents that come into the bright portion is the whole of Europe, Africa, the Atlantic Ocean, North and South America. When the globe rotates further, Australia, Japan, and Indonesia are seen. Then we see India again! This happens when the globe has taken one whole rotation. When we saw America in the bright portion, we could not see India. This is because India had moved to the darker portion.

The Earth rotates around its axis. In one complete rotation, every country has gone through one complete bright and one complete dark portion. So a person standing in one position on the earth will see one complete day and one complete night during one rotation (1 day) of the Earth. Thus, we have day and night.

9

http://www.msnucleus.org/membership/html/k-6/uc/earth/1/uce1_1a.html

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Fig. 10: Day and night on Earth10

KEY MESSAGE  

10

Days and nights occur due to the rotation of the Earth around its axis.

One day and night is one complete earth rotation.

http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question31.html

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ABL 2.4

Time: 15 min

LEARNING OBJECTIVE: To learn how seasons occur.

ADVANCE PREPARATION Material List: Season Model Things to do Ensure that the room where the activity is to take place can be made into a dark room. This can be done by covering all the windows with dark cloth or paper and closing the doors and putting off all the lights.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect about Earth’s revolution from activity 2.1 Procedure Ask the students to explain seasons. Ask them to come out with the characteristics of different seasons. Ask them why these seasons occur.

Now take the plain paper perpendicular to the beam of light from the torch. Observe what is seen.

Then tilt the paper to an angle. Ask the students to observe the distribution of intensity of light on all parts of the paper.

To operate the season model use the handle. Ask the student to observe the amount of light on all side of the globe.

UNDERSTANDING THE ACTIVITY Leading questions 1. What are the different seasons? When do we say it is winter or summer?

2. Initially when the beam of light falls on the paper, what do you see?

3. Then, when the paper is tilted, what do you observe?

4. Can you compare your observation with the model?

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The hot longer days are seen in summer. The winters have cold and short days.

Initially, when the paper is held perpendicular to the beam of light, the beam forms a circle of light on the paper. The intensity of light is equal in all directions. Then, when the paper is tilted, the circle of light changes to an elliptical form. The part of the ellipse nearer to the torch is brighter and the one further away is lighter.

This is similar to the Earth. The Earth is also tilted at an angle of 23.5 0.

The main reasons for the seasons are  The Earth’s axial tilt  The revolution of the earth around the sun This means that sunlight falls on the same place on the earth at different angles at different times.

This is also responsible for the variation in the duration of days and nights at different times of the year and in different places.

Because of the axial tilt of the Earth, one hemisphere of the Earth is more towards the Sun than the other. As the Earth goes around the Sun, the other hemisphere comes nearer the Sun; whichever hemisphere is closer to the Sun has summer as the distance covered by the sunrays is shorter and more concentrated. During winter, the sunrays are slanting and so less hot. This is shown in figure 11.

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Fig. 11: Occurrence of Seasons11 As you can see in the model the light bulb represents the sun and the globe representing the Earth is tilted 23.50 Operate the model in the counter clockwise direction. Because of the axial tilt of the globe, one hemisphere of the globe is more towards the light bulb (sun) than the other. In the fig 11 it is summer for the northern hemisphere while it is winter for the southern hemisphere. As you rotate the model, the other hemisphere comes nearer the light bulb; whichever hemisphere is closer to the Sun has summer while it is winter for the other hemisphere.

We must remember that the Sun is stationary but because of the axial tilt of the Earth, its rotation and revolution around the Sun, we feel that the Sun moves from one hemisphere to the other. The Sun moves till the Tropic of Cancer in the Northern Hemisphere. This time there is summer in the Northern Hemisphere and winter in the Southern Hemisphere. Then it goes to the south till the Tropic of Capricorn. This time the Southern Hemisphere will have summer and the Northern Hemisphere will have winter.

You can observe the same in the model.

During the shift of the Sun from one hemisphere to the other, there is a time when the Sun is directly above the equator. This happens twice in one revolution. This is known as Equinox. This occurs on March 21 or 22 each year (called the Vernal Equinox) and also on September 22 or 23 (called the Autumnal Equinox).

Fig. 12: Formation of Seasons12

11

http://www.weatherquestions.com/What_causes_the_seasons.htm

12

http://facstaff.gpc.edu/~pgore/Earth&Space/GPS/seasons.html

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The fig12 shows the Earth with tilted axis revolving around the Sun, and how this relates to the seasons in the northern and southern hemispheres. Note that the axis is always tilted in the same direction. When the axis and pole point toward the sun, it is summer in that hemisphere. When the axis and pole point away from the sun, it is winter in that hemisphere.

In the model, the orbit of the Earth around the sun is circular. But in reality it is an ellipse. But the seasons are not the result of the variation in Earth's distance to the sun because of its elliptical orbit. In general, the effect of the Earth’s elliptical orbit is only a 7% variation in sunlight received on Earth.

KEY MESSAGE 

Seasons occur due to the axial tilt of the Earth and its revolution around the Sun.

INTERESTING INFORMATION     

When there is summer in the northern hemisphere there will be winter in the southern hemisphere as the northern hemisphere is tilted towards the sun from March to June.

From September to December it is summer in the southern hemisphere and winter in the northern hemisphere The poles have only two seasons, summer and winter, of six months duration each.

Places between the poles and the tropics have four seasons. They gradually change from spring to summer during March to May and from autumn to winter during September to December.\ In India, there are 6 seasons. They are: • March, April _ Vasanth September, October _ Sharath • May, June _ Greeshma November, December _ Hemantha

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  

• July, August _ Varsha January, February _ Shishira On 21st March and 23rd September, the sun is exactly over the equator and the duration of day and night is equal (12 hours) at every place on the earth.

From March 21st to June 21st, the sun moves from the equator to the Tropic of Cancer in the northern hemisphere. Hence, days become longer and nights become shorter in the northern hemisphere.

From June 21st to December 22nd, the sun moves towards the Tropic of Capricorn. Due to this the days become shorter and the nights longer in the northern hemisphere.

VOCABULARY Axial Tilt of the Earth: The axis of the Earth is leaning towards the path of the orbit of the Earth around the Sun. This is called the axial tilt of the Earth. This is one of the reasons we have seasons.

The Earth’s axis is tilted about 23.5 degrees.

Tropic of Cancer: The latitude 23°27′ north of the equator is the most northerly latitude at which the sun can shine directly overhead. This is called the Tropic of Cancer.

Tropic of Capricorn: The latitude 23°27′ south of the equator is the most southerly latitude at which the sun can shine directly overhead. This is called the Tropic of Capricorn.

Equinox: The Equinox is when the Sun is directly over the equator. This happens twice in a year and at this time; the lengths of the day and night are equal at all places of Earth.

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44 Time: 15 min

ABL 2.5 LEARNING OBJECTIVE - (a) Understanding retrograde motion ADVANCE PREPARATION Material List: Not Applicable Things to do The activity will be done in a large empty room or in the playground. So permission to take the students out in the open should be obtained before the class starts.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Not Applicable Procedure Get all the students to the ground. Draw two nearly elliptical orbits similar to Earth and Mars orbit (Check the orbit of earth and mars from activity 1.2). Ask two students to join you. We will call them student 1 and 2. Mark a point ‘A’ in both the orbits as shown in the figure below

Let student 1 take the inner orbit and student 2 take the outer orbit. Ask both the students to start walking in fairly equal steps in counterclockwise direction in their respective orbit till they reach point ‘A’ again. Observe what happens.

UNDERSTANDING THE ACTIVITY Agastya International Foundation. For Internal Circulation only.

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Leading questions 1. Are both the students walking in their orbit and in which direction?

2. Who reaches point A first?

3. So what do you infer from this activity?

Discussion and Explanation Both the students are walking in their respective orbit in same direction (counterclockwise) with respect to each other. Initially Student 1 feels he/she is far behind student 2. Since student 1 orbit is smaller than student 2 he/she gets closer and closer to student 2. Now student 1 feels that student 2 is coming towards him/her. Then student 1 crosses student 2 and moves towards point ‘A’. Now student 1 feels student 2 is going further away from him in the opposite direction i.e., he/she is travelling in the reverse direction. This motion of student 2 observed by student 1 is called retrograde motion. In this activity, student 1 represents Earth and student 2 represents Mars.

Retrograde means going backwards. As one feels that the movement is in the opposite direction it is also called the apparent retrograde movement.

In Astronomy the most noticeable in the apparent motion of the planet Mars through the sky. As the Earth overtakes the position of the red planet Mars form one night to another among the stars, Mars seems to slow and loops backward and then returns to its normal direction (this takes several weeks or months)13. This retrograde motion is entirely an illusion caused by the Earth passing the slower moving outer planet.

KEY MESSAGE Retrograde motion: It is the apparent motion of an object to move in a direction opposite to that of other object, as seen from a certain reference point.

INTERESTING INFORMATION 

You can test retrograde motion the next time you pass a car on the highway. As you approach the slower car, it is clearly moving in the same direction you are. Right as you pull alongside and pass it, however, the car appears to move backwards for just a moment. As you continue pulling away, the car resumes its forward motion. The same thing happens as Earth passes the slower moving outer planets.

But retrograde movement isn’t always an illusion. There are real retrograde motions in the solar system. Venus rotates in the opposite direction from every other planet! If the clouds ever parted, the Venusians would see the sun rise in the west and set in the east. 14



13

http://wiki.answers.com/Q/What_is_retrograde_motion&src=ansTT

14

http://earthsky.org/space/what-is-retrograde-motion

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ABL 2.5

Time: 15 min

LEARNING OBJECTIVE - (b) Understanding retrograde motion IMPORTANT NOTE: This activity using the working model is only for Kuppam, Bangalore and Hubli campus.

ADVANCE PREPARATION Material List: Retrograde motion - Working Mod Things to do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity This activity is the working model of the previous activity 2.5 (a)

Procedure

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Operate the model by turning the handle.

UNDERSTANDING THE ACTIVITY Leading questions 1. Which sphere is Earth?

2. Which sphere is Mars?

3. Which planet is closer to the sun?

4. What do you infer from this model?

Discussion and Explanation The globe representing Earth and Mars are shown in the figure above. We can observe that the Earth is closer to Sun compared to Mars. So as the model is operated slowly, it appears that the motion of Mars slows down, comes to rest and starts to move backwards related to the earth. The globe representing earth overtakes the globe representing Mars. This apparent motion of an object to move in a direction opposite to that of other object, as seen from a certain reference point is known as Retrograde Motion.

The reasons for this apparent motion are:  Motion is relative.  Orbital periods (Revolution) of different planets are different.  The lengths of orbit (orbital radius) of different planets are different.  It also depends on the line of observation from the earth.

KEY MESSAGE: Retrograde motion of Mars is an apparent motion .

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ABL 3: MOON AND ECLIPSE Activity

Learning Objective

Key Message 

 3.1

Same face of the Moon 

Time

Only one face of the Moon is seen from the Earth at any given time. This is because of the synchronized motion of the moon around the earth.

It is more apt to say that synchronize motion is a type of rotation where the object does not spin about its axis.

The time taken for one rotation and one revolution of the Moon is the same i.e., 27.32 days.

20 min

There are totally 8 phases that our moon goes through in a month, starting from 20 min

3.2

3.3

Phases of the moon

To understand how a Solar Eclipses and Lunar Eclipses occur

       

New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Last Quarter Waning Crescent

 Solar eclipse occurs on a new moon day when the Moon comes in between the Earth and the Sun  Lunar Eclipse occurs on a full moon day when the Earth comes between the Sun and the Moon Total Time

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60 min

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ABL 3.1a

Time: 20 min

LEARNING OBJECTIVE – (a) To understand why we see the same face of the moon from the Earth at all times.

NOTE: Only for class 8 and above

ADVANCE PREPARATION Material List: Take printout of Chart 13, 14, 15 and 16 Things to do Not Applicable Note to Instructor: Remember the moon rotates and revolve around the earth. But its rotation is so synchronized that only one phase of the moon faces the earth all the time. In other words moon does not spin about its axis as the earth does. It just tilts itself showing only one face as it revolves around the earth.

Watch the link below for understanding the same phase of the moon and rotation and revolution period of moon better. http://www.youtube.com/watch?v=OZIB_leg75Q Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect activity 2.1. As the earth rotates and revolves around the sun, the moon also rotations (but do not spin about its axis like earth) and revolves around the earth.

Procedure

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Chart 13 Moon as seen from earth

Chart 14 Far side of Moon

Gather students into a group. Ask them to recollect activity 2.1. Tell them as the earth rotates and revolves around the sun, the moon also rotates and revolves around the earth.

Now show them Chart 13. Ask them what they think about the images. Most students will say it as Moon. Now ask them do we always see the same face of the moon from earth. Answer will be yes.

Now show them Chart 14 and ask them what they think about this image. Most students will not know it is the far side of the moon. Explain to them it is the other side of the moon.

Now raise the question why don’t we see this far side of the moon from earth. Tell them to understand this we have to perform 2 activities.

Make enough space for the activity. Ask one student (student 1) to come to the center of the room. This student represents the Earth. Ask him to turn around slowly to demonstrate that the Earth rotates on its axis.

Now, ask another student (student 2) to step forward. He will represent the Moon.

ACTIVITY 1: We know that the moon revolves around the Earth. As student 1 rotates, ask student 2 to rotate about his/her axis and revolve around the earth slowly. Ask the students to observe the face of the moon (student 2) visible to the earth (student 1). In this activity the student 2 front side refers to Chart 13 the face visible to earth and his back side to Chart 14 the face not visible to earth.

UNDERSTANDING THE ACTIVITY Leading questions 1. How does the moon rotate?

2. Can you see both sides of moon?

3. What do you infer from this activity?

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In this activity 1, the moon rotates about its axis. If it rotates about its axis as the earth does then we would be able to see all sides of the moon. But this is not the case; we have never seen the far side of the moon from earth. The only logical explanation will be the moon revolves around the earth but does not spin about its axis. Then how does it rotate?

ACTIVITY 2: Now as the student 1 rotates, ask student 2 to only revolve around student 1 and not to rotate about his/her axis. As student 2 revolves he/she should always make sure to shown only one side i.e., his front side to student 1. At all times student 1 must only see student 2’s face. For this kind of rotation the student 2 should slightly tilt him/her as he/she revolves and must not spin about his/her axis. Now ask the students to observe the face of the student 2 (moon) visible to student 1(earth).

UNDERSTANDING THE ACTIVITY Leading questions 1. Now how does the moon rotate?

2. Can you see both sides of moon?

3. What do you infer from this activity?

Discussion and Explanation In this activity the moon (student 2) does not spin about its axis as the earth does but tilts itself to ensure only one side of the moon is visible from earth(student 1). So at any time, the student 2 one side is facing student 1. So, only one side of the Moon is facing the Earth all the time. Chart 15 will illustrate this to you.

Chart 15: Same face of the Moon faces the Earth15

15

http://scienceblogs.com/startswithabang/2008/04/29/why-do-we-only-see-one-side-of-the-moon/

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But if the moon does not spin about its axis does it mean it does not rotate. The answer would be ‘NO’. If the Moon did not rotate, we would be able to see different faces of the moon. This is shown in Chart 16 Chart 16: Faces of Moon that are seen from the Earth16

The tilting of the moon in its orbit as it

revolves complete one rotation. In this activity if you observe the rotation and revolution period of moon is the same. As the moon completes one rotation it also completes one revolution. Its rotation and revolution period is 27.3 days.

This is shown in fig 13

Fig 13 Rotation and revolution period of the Moon The yellow arrow represents Moon’s Rotation.

The green arrow represents Moon’s Revolution.

The purple arrow represents the near side of the Moon as seen from earth.

The reason for the moon not to spin about its axis is because it is tidally locked by gravity to earth which ensures rotation and revolution period is the same. This type of rotation is called as Synchronized motion of the moon around the earth.

16

http://soc.haifa.ac.il/~masfur/general1/astronomy/moonhtml.html Agastya International Foundation. For Internal Circulation only.

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KEY MESSAGES   

Only one face of the Moon is seen from the Earth at any given time. This is because of the synchronized motion of the moon around the earth.

It is more apt to say that synchronize motion is a type of rotation where the object does not spin about its axis.

The time taken for one rotation and one revolution of the Moon is the same i.e., 27.32 days.

INTERESTING INFORMATION:    

The face of the moon visible from earth is called the near side.

The face not visible to earth is called the far side.

The far side of the moon cannot be seen without launching a spacecraft.

The first photo of the far side of the moon was taken by the Soviet spacecraft Luna 3 on Oct. 7, 1959.  On moon a day (rotation) and a year (revolution) are the same.

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ABL 3.1b LEARNING OBJECTIVE - (b) To understand why we see the same face of the moon from the Earth at all times.

NOTE: Only for class 8 and above

ADVANCE PREPARATION Material List: Not Applicable Things to do Remember the moon rotates and revolves around the earth. But its rotation is so synchronized that only one face of the moon faces the earth all the time. In other words moon does not spin about its axis as the earth does. It just tilts itself showing only one face as it revolves around the earth.

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Safety Precautions Not Applicable Note to Instructor Ask the students to compare the model to the activity 3.1 (a). First ask the student to explain the model. This gives the instructor a chance to analyze how far the students have understood the concept.

SESSION Link to known information/previous activity Recollect activity 2.1. As the earth rotations and revolves around the sun, the moon also rotations (but do not spin about its axis) and revolves around the earth.

Procedure

Fig 14: Same face of the moon model Operate the model by turning the handle such that the globe representing moon revolves in anticlockwise direction.

UNDERSTANDING THE ACTIVITY Leading questions 1. Does the globe representing the moon spin about its axis as the earth does?

2. What do you observe when the Moon revolves around the Earth?

3. How many rotations does the Moon make in one revolution around the Earth?

4. What does the white and dark part of the moon represent?

Discussion and Explanation From the model we observe that the globe representing the moon does not spin about its axis as the earth. The rotation of the moon is locked by gravity to the earth, so its period (or day) is the Agastya International Foundation. For Internal Circulation only.

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same as its orbital period (or year) around the earth. In other words, it takes the moon the same time to complete 1 rotation and 1 revolution around the earth .This means that we could only see one face of the moon all the time from the earth. We cannot see the far side except by launching the rocket.

The rotation and revolution period of the moon is 27.3days.

In the model, the black portion represents the far side of the moon and the white portion represents the near side of the moon

KEY MESSAGE 

Only one phase of the Moon is visible from the Earth all the time. This is because of the synchronize motion of the moon around the earth.  The time taken for one rotation and one revolution of the Moon is the same i.e., 27.32 days.  One month is one complete moon revolution.

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ABL 3.2

Time: 20 min

LEARNING OBJECTIVE - To understand the Phases of the Moon ADVANCE PREPARATION Material List: Use the same face of the moon model and the light source (from the phases of the moon model) to represent the sun.

Things to do This activity can only be done when the class room is made dark.

Safety Precautions Not Applicable Note to Instructor Activity 3.1 has not been taught for classes below 8 . For these students give an introduction as earth rotates and revolves around the earth, the moon also rotate and revolve around the earth.

Do not go into the detail unless any student raises a question.

SESSION Link to known information/previous activity Recollect activity 3.1 Procedure Fix the light source representing the Sun and the same face of the moon model as shown in the fig 15

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Fig 15 Same face of the moon model 2 Switch on the light source. Slowly rotate the handle in the model in anticlockwise direction such that the globe representing moon revolves in anticlockwise direction. Observe the different phases produced by the bulb on the globe representing moon. The places where the phases of the moon can be observed are given in the fig 16 below.

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Fig 16 Phases of moon Stop at every phase. Explain the concept and then move on to the next phase.

UNDERSTANDING THE ACTIVITY Leading questions 1. What does the phrase ‘phases of moon’ mean?

2. What causes the moon to go through different phases?

3. What are the different types of phases?

Discussion and Explanation The lunar phase or phase of the moon is the shape of the illuminated (sunlit) portion of the Moon as seen from Earth.

The moon is a non-luminous celestial object. It just reflects the light from the sun. Hence the part which reflects sun light (or facing the sun) gets illuminated and the part facing away from the sun is in darkness.

The Moon orbits our planet, and this Earth-Moon system orbits the Sun. As the moon orbits, different parts of it face the sun and get illuminated. The different sunlit portion of the moon as observed from Earth is called as the phases of the moon.

There are two main reason which cause the moon to go through different phases  One as discussed above the phases of the Moon depends on its position in relation to the Sun and Earth.  Second and the most important reason is the 50tilt in the orbital plane of the Moon around the Earth. If there is no tilt in the orbital plane of the Moon we would have solar and lunar eclipses ever month of every year. (Eclipses are discussed in detail in the next activity) There are 8 total phases that our moon goes through, starting from days approximately. The phases of the  New Moon moon are shown in the figure 17.  Waxing Crescent  First Quarter  Waxing Gibbous  Full Moon  Waning Gibbous  Last Quarter  Waning Crescent Finally from the Waning Crescent phase the moon goes back to New moon phase and the cycle continues for every 29.5 Agastya International Foundation. For Internal Circulation only.

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Fig 17 Phases of moon 2

Remember the model does not have the tilt in the orbital plane but in reality the 50 tilt is responsible for the phases. If all these celestial object line up in a straight line we will see an eclipse not a phase. In reality when new moon and full moon occurs the moon is slightly below or above the Earth as shown in Chart 17. Hence most of the month we see different phases of the moon, and not an eclipse. Also an eclipse occurs when the moon, Earth and Sun falls on a straight line. Chart 17 explains the difference between the eclipse and the phases of the moon. The chart is just an artist impression of the eclipse and the phases of the moon. Hence the sun is not in one of the foci of the elliptical orbit but at the center of the earth-moon system.

Chart 17 Differences between Eclipse and Phases of the Moon

New Moon In this phase, the Moon is in-between the Sun and the Earth. Rotate the handle to bring the moon to the new moon position represented by a point in fig 16

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Fig 18: Phases of the moon- New Moon When this happen, the far side of the moon is illuminated and the near side facing the Earth does not receive any sunlight as shown in fig 18. Hence we cannot see the moon from earth during this phase. During this phase the moon rises with the sun and sets with the sun.

Waxing Crescent Rotate the handle in the model in counterclockwise direction till u reach the waxing crescent phase as represented in fig 16. During this phase less than half of the moon is illuminated as shown in fig 19. Crescent moon has a ‘C’ shape. Waxing means growing - so the illuminated part of the moon starts growing slowly.

Fig 19: Phases of the moon- Waxing Crescent First Quarter Rotate the handle in the model in counterclockwise direction again to obtain the First Quarter phase of the moon as shown in fig 16.

During this phase, the moon is half lit i.e., half of the moon is visible. This is shown in fig 20. The moon rises in the noon and sets by midnight. Here again the illuminated portion of the moon starts growing. First quarter phase happens approximately after a week from the new moon phase and also by now the moon would have covered quarter of its orbit around the earth.

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Fig 20: Phases of the moon- First Quarter Waxing Gibbous Rotate the handle again to obtain the Waxing Gibbous phase of the moon as shown in fig 16.

Fig 21: Phases of the moon- Waxing Gibbous During this phase more than half of the moon is visible as shown in fig 21. Waxing means growing – so the illuminated portion of the moon continues to grow.

Full Moon In this phase, the sun, earth and the moon are in a straight line as shown in the model below

Fig 22: Phases of the moon- Full moon Agastya International Foundation. For Internal Circulation only.

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During this phase, the near side of the moon is fully illuminated as shown in the fig 22.This phase occurs approximately a week after the first quarter. The moon rises after sunset and sets by sunrise. By now the moon would have completed half of its revolution around the earth. After this phase the illuminated part of the moon slowly starts decreasing.

Waning Gibbous Rotate the handle again to obtain the Waning Gibbous phase of the moon as shown in fig 16

Fig 23: Phases of the moon- Waning Gibbous During this phase more than half of the moon is visible as shown in fig 23. Waning means decreasing – so the illuminated part of the moon starts decreasing.

Last Quarter Rotate the handle in the model in counterclockwise direction again to obtain the last quarter phase of the moon as shown in fig 16.

Fig 24: Phases of the moon- Last Quarter During this phase, the moon is half lit i.e., half of the moon is visible. This is shown in fig 24. The moon rises in the midnight and sets by noon. Here again the illuminated portion of the moon continues to decrease. Last quarter phase happens approximately after a week from the full moon phase and also by now the moon would have covered 3/4th quarter of its orbit around the earth.

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Waning Crescent Rotate the handle in the model in counterclockwise direction till u reach the waning crescent phase as shown in fig 16.

Fig 25: Phases of the moon- Waning Crescent During this phase less than half of the moon is illuminated as shown in fig 25. Crescent moon has a ‘C’ shape. Waning means decreasing - so the illuminated part of the moon continues to decrease.

Finally, a week later, the moon is back to its new moon starting position as it completes one complete revolution around the earth and again the phases of the moon cycle continues. The time period from one new moon to another is nothing but a lunar month approximately 29.5 days i.e., a month on Earth. Also by the time our earth completes one revolution around the sun, the moon completes 12 revolutions around the earth. Thus we have 12 months in a year. Hence we could see a new cycle of phases of the moon every month.

KEY MESSAGE There are totally 8 phases that our moon goes through in a month, starting from  New Moon  Waxing Crescent  First Quarter  Waxing Gibbous  Full Moon  Waning Gibbous  Last Quarter  Waning Crescent

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65 Time: 20 min

ABL 3.3 LEARNING OBJECTIVE: To understand how Eclipses occurs ADVANCE PREPARATION Material List Solar and Lunar eclipse –Working Model Things to do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect activity 3.1 and 3.2 Procedure

Fig 26: Model representing solar eclipse Operate the model by turning the handle slowly and observe the movements of the earth and moon around the sun. The globe representing the sun, earth and moon are shown in the fig26

UNDERSTANDING THE ACTIVITY Agastya International Foundation. For Internal Circulation only.

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Leading questions 1. What do you observe when the model is operated?

2. What is an eclipse?

3. When does it occur?

4. What are the types of eclipse?

5. Why do not we have eclipse every moon?

Discussion and Explanation As the model is operated, we observe the moon is rotating (but not spinning about its axis) and revolving around earth. Similarly the earth along with moon is rotating and revolving around the sun.

When the sun, moon and the earth come in a straight line, an eclipse is formed.

Since the sun is stationary with respect to our solar system and the earth along with the moon revolves around the sun, there are two possibilities.  The moon can come in between the sun and the earth – Solar Eclipse  The earth can come in between the sun and the moon – Lunar Eclipse Solar Eclipse An eclipse of the sun or a solar eclipse can happen only on a new moon day when the moon is in between the sun and the earth.

When the model is operated, at some stage the moon is in between the sun and the earth and the shadow of the moon falls on some regions of the earth.

The moons shadow actually has two parts  Penumbra – The moon’s faint outer shadow  Umbra– The moon’s dark inner shadow This is shown in Chart 18.

Chart 18 Solar Eclipse Agastya International Foundation. For Internal Circulation only.

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When the Moon's shadow falls upon Earth's surface, the people who live in the area where the shadow falls will not see the Sun as the Moon is blocking the Sun rays reaching the Earth. 'To Eclipse' means to hide. Here the Sun is hidden and so it is called the Solar Eclipse.

The people who are in the Umbra region will see a complete eclipse or total solar eclipse, i.e., the whole Sun will be blocked by the moon. Those who live in the Penumbra region will see a partial solar eclipse i.e., only some part of the Sun will be blocked by the moon.

The Moon comes between the Sun and the Earth once every month on the new moon day. But we do not see the solar eclipse every month. This is because the Moon's orbit around Earth is tilted 5 degrees to Earth's orbit around the Sun. As a result, the Moon's shadow usually misses Earth as it passes above or below earth on New Moon day. But twice a year, the geometry lines up just right so that some part of the Moon's shadow falls on Earth's surface and an eclipse of the Sun is seen from that region.

There are four types of solar eclipses  Total, when the sun is completely obscured by the moon.  Annular, when the sun and moon are exactly in line, but apparent size of the moon is smaller than that of the sun.  Hybrid, an intermediate between a total and an annular eclipse.  Partial, when the sun and moon are not exactly in line, and moon only partially obscures the sun.

Lunar Eclipse An eclipse of the Moon (or lunar eclipse) can only occur at Full Moon and only if the Moon passes through some portion of Earth's shadow as Earth is in between the moon and the sun.

As the model is operated, at some point the Earth comes between the Sun and the Moon and the Earth's shadow falls on the Moon.

The Earth’s shadow is actually composed of two cone-shaped components  The outer or penumbra shadow is a zone where the Earth blocks part but not all of the Sun's rays from reaching the Moon.  The inner or umbra shadow is a region where the Earth blocks all direct sunlight from reaching the Moon.

This is shown in Chart 19.

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Chart 19: Lunar Eclipse When the Earth’s shadow falls on the moon, the people who live in the area facing the Moon will not be able to see it as the Earth is blocking the Sun rays falling on the Moon. 'Lunar' is a word associated with the Moon. Here, the Moon is hidden and so it is called the Lunar Eclipse.

Earth comes between the Sun and the Moon once every month on the full moon day. But we do not see the lunar eclipse every month. This is because the Moon's orbit around Earth is tilted about 5 degrees to Earth's orbit around the Sun. During Full Moon, the moon usually passes above or below Earth's shadows and no eclipse occurs. But two to five times each year, the Moon passes through some portion of the Earth's penumbral or umbra shadows and one of the below three types of eclipses occurs.

There are three basic types of lunar eclipses:  Penumbral- the Moon passes through Earth's penumbral shadow.  Partial - A portion of the Moon passes through Earth's umbra shadow.  Total - The entire Moon passes through Earth's umbra shadow.

KEY MESSAGES  Solar eclipse occurs on a new moon day when the Moon comes in between the Earth and the Sun  Lunar Eclipse occurs on a full moon day when the Earth comes between the Sun and the Moon

INTERESTING INFORMATION  Usually, lunar eclipses come in no particular order. A partial can be followed by a total, followed by a penumbral, and so on. But when four consecutive lunar eclipses are all total, the series is called a tetrad.  There are a total of 8 tetrads in the 21st century (2001 to 2100) of which this year (2014) and next year (2015) marks the second tetrad. The dates for the on-going tetrad are as follows: Agastya International Foundation. For Internal Circulation only.

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2014: Total lunar eclipse: April 14-15 Total lunar eclipse: October 7-8 2015: Total lunar eclipse: April 4 Total lunar eclipse: September 28  This year, there are two solar eclipses and two total lunar eclipses.  2014 Apr 15: Total Lunar Eclipse  2014 Apr 29: Annular Solar Eclipse  2014 Oct 08: Total Lunar Eclipse  2014 Oct 23: Partial Solar Eclipse  One should never look at the sun with naked eyes, and never during the solar eclipse as it can damage our eyes. Special glasses, with filters are available in the market to view the eclipse. Alternatively, solar scope can be used.  Unlike solar eclipses, lunar eclipses are completely safe to watch. You don't need any kind of protective filters or telescope.

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ABL 4: CONSTELLATIONS S. No.

Learning objective 

4.1

To identify the starts in the sky 

4.2

The Celestial Sphere

Key message

Time

A group of stars forming a pattern is called a constellation.

30 min

A group of stars forming a pattern is called a constellation.

30 min



By locating the North Star Polaris we can find direction in the night.



The path of the Sun on the celestial sphere is called the Ecliptic.

TOTAL 60 min

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71 Time: 30 min

ABL 4.1 LEARNING OBJECTIVE To identify the starts in the sky ADVANCE PREPARATION Material List: S. No. 1 2

Materials Projector Transparencies

Quantity 1/class 4/ class OR

1 2

Torch with a stand A 4 size cardboards

1 per class 4/ class

Things to do The classroom should be prepared to project the image on the screen or a plain wall. Get the projector or the torch stand positioned so that the image is seen clearly. Select any four constellations and draw them on the transparencies, one on each transparency. If you are using the torch, mark the constellations on the cardboard and punch holes on the stars that make up the constellations. The cardboards will be kept in front of the torch and the light passing through the holes in the cardboard will form an image on the wall/screen. Try this out before the class starts.

Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect ABL 1.1.

Procedure Ask the students what they see in the sky at night. When they say Moon and the stars, ask them more about the stars.

Tell them that there are so many stars that it was difficult to recognize them all. So man decided to group some stars together because he thought they looked like a human or an animal. He named them. These groups of stars are called constellations. Tell them that they are going to study 4 of the 88 constellations that man has identified.

Project one of the constellations and explain to them that they are the brightest stars in that area of the sky. Sometimes the not-so-bright star is also included so that the figure is complete. Show the students the 4 constellations that you have selected and names of some stars in the constellations. (The figures of some constellations and the web sources where information about them is available is given at the end of the activity) Agastya International Foundation. For Internal Circulation only.

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UNDERSTANDING THE ACTIVITY Leading questions 1. What do you see at night in the sky?

2. Why are the stars not seen clearly when there is a Moon?

3. How can individual stars be recognized?

4. Can you recognize any of the constellations?

5. Some time planets also appear as bright bodies. How do you distinguish them from stars?

Discussion and Explanation If we look into the sky we can see a number of twinkling stars. The Sun is our nearest star, other stars are millions of times farther from the sun. The feeble stellar light is masked in the bright and intense Sun light. During day time in the presence of sun light, it is not possible to see the stars.

Again, if it is a bright moon during night we may not be able to spot many of the stars and study the constellations.

A clear night of a new moon day is best preferred for star watching. Some stars like Polaris are easily recognized.

To recognize other stars, our ancient astronomers have tried to divide the stars into groups called constellations named on the basis of the geometric shape or pattern (mostly a mythological figure) they form. These constellations were useful tools for navigation in olden days and for reckoning time during night times.

Planets which also look like bright objects should not be confused for stars. Planets o not twinkle where as stars do twinkle.

KEY MESSAGES 

A group of stars forming a pattern is called a constellation. The constellations are traditionally named after its apparent geometrical pattern or identified with a mythological figure.

INTERESTING INFORMATION People have used constellations for many different reasons. And these reasons have changed throughout history. Astronomy is the oldest science. This is because even the earliest cavemen would look up at the sky and wonder about what makes it run. People saw that the motions of the stars were regular and predictable.

The first use for Constellations was probably religious. People thought that the Gods lived in the heavens and that they created them. Many cultures believed that the positions of the stars were Agastya International Foundation. For Internal Circulation only.

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their God's way of telling stories. So it seemed natural to recognize patterns in the sky, give them names, and tell stories about them. We inherited the names for our constellations from the Greeks. And they named the constellations after their mythological heroes and legends. So behind every constellation there is a story. For example, to the ancient Greeks, Orion was a great hunter.

He was the son of Neptune (god of the sea). But the same stars were considered to depict Osiris by the Egyptians. Each different culture developed their own interpretation.

A more practical use for constellations was agriculture. Before there were proper calendars people had no way of determining when to sow, or harvest except by relating to the stars. Constellations made the patterns of the stars easy to remember. The ancient peoples knew for example that when the constellation Orion started to be fully visible winter was coming soon. Or they could look at the Summer Triangle to know when Summer or Spring were coming as well. The stars allowed farmers to plan ahead and form agriculture, and constellations made it easier to recognize and interpret the patterns in the sky. Four or five decades ago the rural Indian folk had to depend on the stellar positions to guess time at night.

The constellations also helped with navigation. It is fairly easy to spot Polaris (The North Star) once you've found Ursa Minor (Little Dipper constellation). One can figure out his/her latitude (North/South) just by looking at how high Polaris appears in the night sky. This allowed for ships to travel across the globe. It allowed for the discovery of America, the spread of European culture, and civilization as we know it today17.

LEARNING CHECK  

Find out more about different constellations from reference books.

You can also find out about stories or myths behind stars and constellations from people at home. Elderly people do know about these things.

WEB RESOURCES 1. Excellent program to learn to recognize the constellations - instructors should do it at least once, get the students to do it too if there is provision of computer and internet connectivity http://shadowsnook.com/MAG/Stuff/NightSky/Pages/032.html () 2. To make Flash cards of the constellations http://www.science-teachers.com/constellation_flashcards.htm

17

http://curious.astro.cornell.edu/question.php?number=340

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ABL 4.2

Time: 30 min

LEARNING OBJECTIVE – The Celestial Sphere ADVANCE PREPARATION Material List: Star Ball Things to do Not Applicable Safety Precautions Not Applicable

SESSION Link to known information/previous activity Recollect ABL 4.1.

Procedure Make the students to sit in a circle. Pass the star ball to each student and ask them to identify the constellation.

UNDERSTANDING THE ACTIVITY Leading questions 1. What does the ball represent?

2. What does the pattern in the ball represents?

3. What is ecliptic?

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Discussion and Explanation The ball represents the celestial sphere. The celestial sphere is an imaginary sphere of gigantic radius with the earth located at its center. All other celestial bodies are projected on to the inner surface of this celestial sphere. The poles of the celestial sphere are aligned with the poles of the Earth. The celestial equator lies along the celestial sphere in the same plane that includes the Earth's equator.

Each pattern on the ball represents a constellation. The Pole star, Polaris, points to the Celestial North Pole. By identifying Polaris we can know the direction in the night as Polaris points towards the North. Ask a student to identify the asterism big dipper in Ursa Major Constellations. Ask another student to identify the asterism little dipper in Ursa Minor Constellation. The stars Merak and Dubhe points to the Polaris. This is shown in Chart 20

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Chart 20: Constellations The apparent path of the Sun on the celestial sphere is called the Ecliptic and is the basis for the ecliptic coordinate system. If you notice all the zodiac constellations in the star ball falls on this line and the two point where the ecliptic meets the celestial equator is called the equinox (vernal and autumnal).

Ask each student to identify their zodiac constellations.

KEY MESSAGES   

A group of stars forming a pattern is called a constellation.

By locating the North Star Polaris we can find direction in the night.

The apparent path of the Sun on the celestial sphere is called the Ecliptic.

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TAKE HOME ACTIVITY ACTIVITY 1 How to spot the Milky Way band?

The Milky Way Galaxy is one of the most interesting naked eye sights in the night sky. However, it’s not bright. So to see the Milky Way band from Earth choose clear and dark skies with no moonlight and go as far as you can from any source of light pollution. Give your eyes at least 10-20 minutes to adapt to the darkness though.

Spot the star Vega in Lyra Constellation and Altair in Aquila Constellation. The Milky Way band lies in between these two constellation.

Also the Denab star in Cygnus Constellation and Antares star in Scorpius Constellation can help you spot the Milky Way band. Try to spot the Galactic center.

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ACTIVITY 2 Finding your Latitude with a Quadrant If you are in the northern hemisphere you can find the latitude of your location by measuring how high the Pole Star (called Polaris) is above the horizon. Polaris is located in the northern sky at a point close to the North Celestial Pole.

The closer you are to the North Pole in the northern hemisphere, the higher Polaris will be above the horizon. The closer you are to the equator, the lower will be Polaris to the horizon. If you can measure the angle of Polaris from the ground (where you are standing) you will be able to calculate your latitude and also the distance from the equator..

Latitude = Distance from equator A simple astronomical instrument that is used for measuring the angle of a star above the ground is a Quadrant, which was widely used by Muslim astronomers and navigators.

The Instruction to make a quadrant, materials and the procedure to use the quadrant are given in the next three pages respectively.

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How to use a Quadrant:  Wait till the sun sets and find Polaris.  With the arc of the quadrant facing towards you, look along the straight edge, through the tiny gap between the sights.  Line up the star between the sights, so it looks as if it is resting on the end of the quadrant.  Let the string hang down and then hold it in place.  Read of the number on the arc and that gives your latitude (in degrees).  Cut your stars from the template and write you latitude.

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Sun

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

-

5.79

10.82

14.96

77.83

142.7

286.96

1 cosmic year (w.r.t milky way galaxy)

87.97da ys

224.7 days

365.25d ays (= 1 year)

22.67 9 1.9 years

Neptun e 449.66

11.8 years

29.46 years

84.01ye ars

164.8 years

Has different rotation period for equator and poles

58.65 days

243 days

24h 37 m

9h 51m

10 h14 m

17 h 14m

16 h3m

-

00

1780

23h 56m 4s (= 1 day) 23.450

250

3.120

26.70

97.90

29.60

-

70

3.390

00

1.850

1.30

2.490

0.770

1.770

13,92,000

4878

12104

12756

6796

1,43,800

50,800

49,500

Mass (Compar ed to earth) Rings

3,33,000

0.0553

0.815

1

0.108

318

1,20,66 0 95.2

14.6

17.2

No

No

No

No

Average Surface tempera ture Atmosph ere Main compon ents

5,500 0C (core) 1,50,00,0 000C Plasma

1790 C

4800C

150C

-230C

Thin ,dim -1500C

Bright ring -1850C

Possess rings -2100C

Possess rings -2180C

No

Dense

Dense

Thin

H95%,He4%, others 1%

No

Co296%,N3%,othe rs

N 78%,o21%, and others

Dense ,thick H-97%, He,CH4, NH3

Dense, thick H83%,He 15%, Ch4,acet alin

Dense, thick H75%,He 20%,ch4, ch3

Surface

Sun spots

Solid

Solid

Surface materials

Solar flares prominen ces

Solid surface Many craters rocks

Co295%,n 3%,ar, CO 0.007 solid

Thin ,dense H-90% ,He,CH4, NH3

rocks, volcano es, mounta

rocks mounta ins, soil water,

Crater s, lava, solid

Not solid Gas giant hydroge n liquid

Not solid Gas giant hydroge n liquid

Not solid Gas giant H,liq.H

Not solid Gas giant

Average distance Revoluti on period (w.r.t earth days) Rotation period (w.r.t.

Earth) Inclinatio n of the axis to ecliptic Inclinatio n of the orbit to ecliptic Diameter

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Color of the planet

Name of the discover er Year of discover y

White

ins, lava 80%

plants animals .

co2, iron oxide.

H

H

Grey

Yellowis h White

Light Blue with White clouds

RedOrang e

orange and white bands

Pale Yellow

Bluish green

Light blue

Babyloni ans

Ancient s

Ancie nts

Ancients

Ancient s

William Hershel

Johan galle

1781

1846

264 B.C

Table 1: Planets Information Chart

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