What is space by jonathan granger

WHAT IS SPACE ?

Designed & Illustrated by Jonathan Granger www.jonathangranger.com

This is a book illustrating what I have learnt through out my own personal journey in outer space exploration. Most things you may have stumbled across before but I have tried to take a new fun interesting approach that will rekindle old interests and spark new ones.

What Is Space ?

Space is the limitless, boundless, three dimensional extent where objects and events occur and have relative position and direction.

Generally, physical space is conceived in 3 linear dimensions, although modern physicists typically consider it (along with time) to be part of the boundless four dimensional continuum that is known as spacetime. In the world of mathematics, â&#x20AC;&#x2DC;spacesâ&#x20AC;&#x2122; are usually examined with different numbers of dimensions and with differentunderlying structures. Space, the concept, is generally considered to be of critical importance to an understanding of the physical universe ,although philosophers disagree about whether space is itself an entity, a relationship betweenentities, or part of

a conceptual framework. In the view of the great English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian Isaac Newton (1643-1727), space was absolute. In the sense that it existed permanently and independently of whether there were any matter in the space. Other philosophers such as Gottfried Leibniz, thought instead that space was a collection of relations between objects, given by their distance and direction from each another.

philosopher Immanuel Kant described space and time as elements of a systematic framework that humans use to structure their experience. In 1905, the brilliant theoretical physicist and philosopher, Albert Einstein, published a paper on a special theory of relativity, where he proposed that space and time be combined into a single construct known as spacetime.

In the 18th century, the German 5

How Did Space Start? Time, space and matter all began with the Big Bang.

Most astronomers believe the Universe began in a Big Bang about 14 billion years ago. At that time, the entire Universe was inside a bubble that was thousands of times smaller than a pinhead. It was hotter and denser than anything we can imagine. Then it suddenly exploded. The Universe that we know was born. Time, space and matter all began with the Big Bang. In a fraction of a second, the Universe grew from smaller than a single atom to bigger than a galaxy And it kept on growing at a fantastic rate. It is still expanding today. As the Universe expanded and cooled, energy changed into particles of matter and antimatter. These two opposite types of particles largely destroyed each other. But some matter survived. More stable particles called protons and neutrons started to form when the Universe was one second old.Over the next three minutes, the temperature dropped below 1 billion degrees Celsius. It was now cool enough for the protons and neutrons to come together, forming hydrogen and helium nuclei.After 300 000 years, the Universe had cooled to about 3000 degrees. Atomic nuclei could finally capture electrons to form atoms. The Universe filled with clouds of hydrogen and helium gas.

BANG 6

BANG

TNT 7

How Big Is Space? That is a question man has been asking since the beginning of time.

When your grandparents were in school, it was thought that the Universe was very small, perhaps only 5000 light years across. 500 years ago it was thought that the Universe was only a little bit bigger than the Earth. In modern times, with the power of technology, we are finally starting to grasp the immense size of the Universe, and it is much bigger than anyone could have ever imagined. When it comes to asking big questions, how big is space is the biggest one. To the best knowledge of astronomers, space is infinite. We can not observe a small portion of all of the universe. We are only able to see the tiny bite that has emitted light that has been able to reach us. What is even more daunting is the fact that the universe is still expanding; therefore, getting bigger as we speak. Scientists cannot stretch a measuring tape from the Earth to a nearby star, so how do they know how far away they are? Scientists use something called Parallax. Parallax means simply that they look at how much the stars move in the sky back and forth throughout the year as the Earth circles the Sun. This is not something unfamiliar to you. In fact, if you stretch out your hand in front of you and look at your thumb while taking turns covering one eye and then the other, your thumb will appear to move back and forth. Stars do the same thing, but our eyes are much too close to see the difference. However, if we take a picture while on one side of Earthâ&#x20AC;&#x2122;s orbit, and then take another when we get to the opposite side of the orbit, then we have a large enough distance that we can see the stars parallax, and determine how far away they really are.

What Is The Solar System? The Solar System is made up of all the planets that orbit our Sun.

In addition to planets, the Solar System also consists of moons, comets, asteroids, minor planets, and dust and gas.Everything in the Solar System orbits or revolves around the Sun. The Sun contains around 98% of all the material in the Solar System. The larger an object is, the more gravity it has. Because the Sun is so large, its powerful gravity attracts all the other objects in the Solar System towards it. At the same time, these objects, which are moving very rapidly, try to fly away from the Sun, outward into the emptiness of outer space. The result of the planets trying to fly away, at the same time that the Sun is trying to pull them inward is that they become trapped half-way in between. Balanced between flying towards the Sun, and escaping into space, they spend eternity orbiting around their parent star.

How Did The Solar System Form? Scientists believe that the Solar System evolved from a giant cloud of dust and gas.

This is an important question, and one that is difficult for scientists to understand. After all, the creation of our Solar System took place billions of years before there were any people around to witness it. Our own evolution is tied closely to the evolution of the Solar System. Thus, without understanding from where the Solar System came from, it is difficult to comprehend how mankind came to be. Scientists believe that the Solar System evolved from a giant cloud of dust and gas. They believe that this dust and gas began to collapse under the weight of its own gravity. As it did so, the matter contained within this could begin moving in a giant circle, much like the water in a drain moves around the center of the drain in a circle. At the center of this spinning cloud, a small star began to form. This star grew larger and larger as it collected more and more of the dust and gas that collapsed into it. Further away from the center of this mass where the star was forming, there were smaller clumps of dust and gas that were also collapsing. The star in the center eventually ignited forming our Sun, while the smaller clumps became the planets, minor planets, moons, comets, and asteroids.

Current estimates puts the age of the solar system at 4.5 billion years old. 14

Asteroid Belt, And The Oort Cloud The Asteroid Belt It is made up of thousands of objects too small to be considered planets.

It is true that there are only eight planets. However, the Solar System is made up of over 100 worlds that are every bit as fascinating. Some of these minor planets, and moons are actually larger than the planet Mercury! Others, such as Io, have active volcanoes. Europa has a liquid water ocean, while Titan has lakes, rivers, and oceans of liquid Methane. The Asteroid Belt, The Kuiper Belt, And The Oort Cloud. You have probably heard about the Asteroid Belt. This band of asteroids sits between the orbits of the planets Jupiter and Mars. It is made up of thousands of objects too small to be considered planets. Some of them no larger than a grain of dust, while others, like Eros can be more than 100 miles across. A few, like Ida, even have their own moons. Further out, beyond the orbit of the minor planet Pluto, sits another belt known as the Kuiper Belt. Like the Asteroid Belt, the Kuiper Belt is also made up of thousands, possibly even millions of objects too small to be considered planets. A few of these objects, like Pluto, are large enough that their gravity has pulled them into a sphere shape. These objects are made out of mostly frozen gas with small amounts of dust. They are often called dirty snowballs. However, you probably know them by their other name... comets. Every once in a while one of these comets will be thrown off of its orbit in the Kuiper Belt and hurled towards the inner Solar System Where it slowly melts in a fantastic show of tail and light. Beyond the Kuiper Belt sits a vast area known as the Oort Cloud. Here within this jumbled disorganized cloud live millions of additional comets. These comets do not orbit the Sun in a ring or belt. Instead, each one buzzes around in a completely random direction, and at extremely high velocities.

Beyond The Oort Cloud The Sunâ&#x20AC;&#x2122;s solar winds continue pushing outward until they finally begin to mix into the interstellar medium, becoming lost with the winds from other stars. This creates a sort of bubble called the Heliosphere. Scientists define the boundaries of the Solar System as being the border of the Heliosphere, or at the place where the solar winds from the Sun mix with the winds from other stars. The Heliosphere extends out from the Sun to a distance of about 15 billion miles, which is more than 160 times further from the Sun than is the Earth.

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Quasars

Quasars are the brightest objects in our universe,

Quasars are extremely distant objects in our known universe. They are the furthest objects away from our galaxy that can be seen. Quasars are extremely bright masses of energy and light. The name quasar is actually short for quasi-stellar radio source or quasi-stellar object. Quasars are the brightest objects in our universe, although to see one through a telescope they do not look that bright at all. This is because quasars are so far away. They emit radio waves, x-rays and light waves. Quasars appear as faint red stars to us here on Earth. A quasar is believed to be a supermassive black hole surrounded by an accretion disk. An accretion disk is a flat, disk-like structure of gas that rapidly spirals around a larger object, like a black hole, a new star, a white dwarf, etc. A quasar gradually attracts this gas and sometimes other stars or or even small galaxies with their superstrong gravity. These objects get sucked into the black hole. When a galaxy, star or gas is absorbed into a quasar in such a way, the result is a massive collision of matter that causes a gigantic explosive output of radiation energy and light. This great burst of energy results in a flare, which is a distinct characteristic of quasars. The light, radiation and radio waves from these galaxies and stars being absorbed into a black hole travel billions of light years through space. When we look at quasars which are 10-15 billion light years away, we are looking 10-15 billion years into the past. Pretty amazing, right?

1. Backh hole 2. Accretion disk 3. Magnetic feild lines 4. Jet of high speed particles 21

A nebula is a cloud of gas and dust in outer space. These clouds are often very large, 22

spanning across many light years. There are many different kinds of nebulae in the sky Emission Nebulae Reflection Nebulae Planetary Nebulae Bok Globule 23

Emission Nebulae Scientists believe that new stars are born form inside of nebulae.

Sometimes the dust and gas in these nebulae clouds begins to contract, or squash together. When things such as clouds contract they get hotter. The denser the cloud gets the hotter it gets. Eventually it gets dense enough and hot enough to ignite its hydrogen fuel, beginning its new life as a star. The first type of nebulae we are going to explore are called Emission Nebulae, because they emit their own light. How do they emit light? They glow red or pink as they expel extra energy which they get from nearby stars. Bright stars inside the clouds charge hydrogen gas with extra energy. The hydrogen in these clouds does not like to be charged and so they get rid of the extra energy by emitting it in the form of red light. The cloud itself is actually glowing. Just like a neon sign.

Remember: A red or pink nebula is called an Emission Nebula and glows because it is getting rid of the extra energy given to it by nearby stars. 25

Reflection Nebulae A blue relfection nebula is completely different from an emission nebula. This is because rather than emitting their own light, they are reflecting the light of the stars around them.

Why Are They Blue? Reflection nebulae are blue for the same reason our sky is blue. They reflect the light of a star. Our sky is reflecting the light of the sun.When light passes by a particle of dust, the blue color in that light is scattered , while the rest of the colors in the light are allowed to travel undisturbed. This blue light travels around the cloud bouncing off of dust particle after dust particle until it eventually escapes the cloud and reaches our eyes.

Remember: A blue nebula is called a reflection nebula. It scatters the blue light from nearby stars while the rest of the colors are allowed to pass through the cloud undisturbed. Eventually the blue light escapes the cloud and travels to our eyes. 27

Planetary Nebulae Although this third type of nebula is called a planetary nebula, it actually has nothing to do with planets. A planetary nebula is formed when a dying sunsized star begins to shed its outer layers.

When the Sun begins to die, it will expand and become what is called a giant star. It will grow so large that it may engulf the Earth. After millions of years as a giant star, the Sun will again shrink down to its normal size. As it shrinks, much of its surface layers will be shed, leaving behind a beautiful ring. This ring is only visible for about 50,000 years. Over time, the nebula mixes into surrounding space eventually becoming too thin to see. 28

Bok Globule

Bok Globules are very dense. This means that there is a lot of dust and gas close together inside of the cloud.

A Bok Globule is different than the other types of clouds we have been learning about. Bok Globules are very dense. This means that there is a lot of dust and gas close together inside of the cloud. There is so much dust and gas that it blocks out all the light behind it. First you can see the blue reflection nebula in the background. In front of the reflection nebula is a dark bok globule blocking the view. 30

There are three kinds of Galaxies The only difference between the three is what shape they are. 32

There are billions of Galaxies in the Universe. Some are very small with only a few million stars. While others could have as many as 400 billion stars, or even more. There are three kinds of Galaxies, Spiral, Elliptical, and Irregular. The only difference between the three is what shape they are. 33

Spiral

The most beautiful type of galaxies are Spiral Galaxies. Their long twisting arms are areas where stars are being formed.

Where do the spirals come from? Like ripples in a pond, the spiral arms seen in this kind of galaxy are circling waves. These waves cause new stars to form. That’s right, they are like star farmers, planting star seeds where ever they go. What causes the waves to glow? Some of the new stars created in the wave are very large. Because of their size these large stars glow brighter than their smaller cousins, causing the nearby dust clouds to glow brightly. Thus any area near one of these waves glows like a fluorescent light.In other words you can’t actually see the waves, the spirals that we see are the glowing clouds illuminated by large, hot stars. As the waves move on the clouds behind them dim down, no longer glowing until another wave passes through. Why doesn’t the whole galaxy shine brightly? The large bright stars created in the waves don’t live very long. Their large size makes them burn all their fuel quickly. Usually they die before they ever leave the wave. Only the smaller stars which do not glow brightly survive to leave the waves they formed in.

Elliptical

The stars found in Elliptical Galaxies are often very old.

This is because elliptical galaxies donâ&#x20AC;&#x2122;t actively create new stars. The only stars found with in them were created along time ago.Although they are usually smaller, this type of galaxy can be large. Most have only a few thousand stars, but some can have billions of stars.The stars in an elliptical galaxy are often very close together making the center look like one giant star. If the Earth were inside an elliptical galaxy it would be bright both day and night.

Irregular

Irregular Galaxies are simply all the galaxies which are not spiral or elliptical.

They can look like anything and have many different characteristics. Many irregular galaxies probably used to be spiral, or elliptical until they had some kind of accident which changed them such as crashing with another galaxy.Many other irregular galaxies probably were never spiral or elliptical; they simply didnâ&#x20AC;&#x2122;t evolve that way. 38

The Local Group The “Milky Way” is a translation of the Latin Via Lactea, in turn translated from the Greek (Galaxias), referring to the pale band of light formed by stars in the galactic plane as seen from Earth

There are billions of galaxies in our Universe. Most of these are clumped together in small groups. Our own galaxy which is called The Milky Way Galaxy lies within a group of galaxies that we call The Local Group. The Local Group consists of about 30 galaxies. The three largest are The Andromeda Galaxy, The Milky Way Galaxy, and Triangulum. The Milky Way ? The Milky Way Galaxy, commonly referred to as just the Milky Way, or sometimes simply as the Galaxy, is the home galaxy of the Solar System, and of Earth. It is agreed that the Milky Way is a spiral galaxy, with observations suggesting that it is a barred spiral galaxy. It contains 100-400 billion stars and is estimated to have at least 50 billion planets, 500 million of which could be located in the habitable zone of their parent star. The Milky Way is part of the Local Group of galaxies and is one of around 200 billion galaxies in the observable universe.The Solar System is located in the Milky Way galaxy halfway out from the center, on the inner edge of the Orion–Cygnus Arm. The Sun orbits around the center of the galaxy in a galactic year—once every 225-250 million Earth years.

Andromeda Galaxy

Boรถtes I (dwarf gaaxy)

Triangulum Galaxy

Messier 110

Wolf-Lundmark Melotte

Sextans A

Small Magellanic Cloud

Phoenix Dwarf

A star is a massive, luminous ball of plasma held together by gravity. The nearest star to Earth is the Sun. Most stars are between 1 billion and 10 billion years old. 42

Stars.

When you look at the night sky you can see many beautiful stars. If you are out in the country or camping in the mountains or the desert away from the city lights, you may see thousands of them. You may even be able to see part of the Milky Way. In a town or city, you canâ&#x20AC;&#x2122;t see nearly as many stars because the city lights create a glow in the sky masking many of them.

There are several different kinds of stars in the sky. Some are very big. A couple of stars have been found that are 100 to 200 times larger than the sun. Some very old stars are smaller than the Earth. Scientists study stars and place them in groups based on how they are alike and how they are different.

The Sun

The Sun is by far the largest object in the solar system. It contains more than 99.8% of the total mass of the Solar System (Jupiter contains most of the rest). The Sun is personified in many mythologies: the Greeks called it Helios and the Romans called it Sol.

It is often said that the Sun is an “ordinary” star. That’s true in the sense that there are many others similar to it. But there are many more smaller stars than larger ones; the Sun is in the top 10% by mass. The median size of stars in our galaxy is probably less than half the mass of the Sun. The Sun is, at present, about 70% hydrogen and 28% helium by mass everything else (“metals”) amounts to less than 2%. This changes slowly over time as the Sun converts hydrogen to helium in its core. The outer layers of the Sun exhibit differential rotation: at the equator the surface rotates once every 25.4 days; near the poles it’s as much as 36 days. This odd behavior is due to the fact that the Sun is not a solid body like the Earth. Similar effects are seen in the gas planets. The differential rotation extends considerably down into the interior of the Sun but the core of the Sun rotates as a solid body. Conditions at the Sun’s core (approximately the inner 25% of its radius) are extreme. The temperature is 15.6 million Kelvin and the pressure is 250 billion atmospheres. At the center of the core the Sun’s density is more than 150 times that of water.

The Sun’s power is produced by nuclear fusion reactions. Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium and 5,000,000 tons of energy in the form of gamma rays. As it travels out toward the surface, the energy is continuously absorbed and re-emitted at lower and lower temperatures so that by the time it reaches the surface, it is primarily visible light. For the last 20% of the way to the surface the energy is carried more by convection than by radiation. The surface of the Sun, called the photosphere, is at a temperature of about 5800 K. Sunspots are “cool” regions, only 3800 K (they look dark only by comparison with the surrounding regions). Sunspots can be very large, as much as 50,000 km in diameter. Sunspots are caused by complicated and not very well understood interactions with the Sun’s magnetic field.

Red Dwarf Red dwarf stars are by far the most common type of star in outer space. However, very few stars that you see in the sky are red dwarfs.

This is because they are so small and make very little light. Imagine standing on a mountain. Pretend that there are one million kids 5 miles away holding flashlights, and 20 miles away there is a lighthouse for ships. You will most likely not see any of the flashlights, while you will very easily see the lighthouse. If the flashlights all glowed as brightly as the lighthouse they would blind you. Likewise, if all the red dwarf stars glowed as bright as the bigger stars, our nighttime sky would be very bright. Why are red dwarf stars red? Because red dwarf stars only burn a little bit of fuel at a time, they are not very hot compared to other stars. Think of a fire. The coolest part of the fire is at the top of the flame where it glows red, the hotter part in the middle glows yellow, and the hottest part near the fuel glows blue. Stars work the same way. Their temperature determines what color they are. Thus, we can determine how hot a star is just by its color.Red dwarf stars are by far the most common type of star in outer space. However, very few stars that you see in the sky are red dwarfs. This is because they are so small and make very little light. Imagine standing on a mountain. Pretend that there are one million kids 5 miles away holding flashlights, and 20 miles away there is a lighthouse for ships. You will most likely not see any of the flashlights, while you will very easily see the lighthouse. If the flashlights all glowed as brightly as the lighthouse they would blind you. Likewise, if all the red dwarf stars glowed as bright as the bigger stars, our nighttime sky would be very bright.

Yellow Star Like the Sun, these medium-sized stars are yellow because they have a medium temperature. Their higher temperature causes them to burn their fuel faster. This means they will not live as long, only about 10 billion years or so. Near the end of their lives these medium-sized stars swell up, becoming very large. When this happens to the Sun, it will grow large enough to engulf even the Earth. Eventually they shrink again, leaving behind most of their gas. This gas forms a beautiful cloud around the star called a Planetary Nebula. When will the Sun expand into a giant, and then shrink leaving behind a planetary nebula?Donâ&#x20AC;&#x2122;t worry, the sun is only about 5 billion years old. It still has another 5 billion years or so before it will expand and turn into a planetary nebula. The Sun is so hot that when it dies, it will take a long time to cool off. The Sun will die in about 5 billion years, but it will still glow for many billions of years after that. As it cools, it will be what is called a white dwarf star. Eventually, after billions, maybe even trillions of years, it will stop glowing. At that point it will be what we call a black dwarf star. Because the process for a star to become a black dwarf takes such a long time, it is believed there are still no black dwarf stars in the universe.

Blue Giant Because blue giant stars only live a short time, scientists use them to find places in outer space where new stars are forming.

Blue stars are large and compact, this causes them to burn their fuel quickly which in turn makes their temperature very hot. These stars often run out of fuel in only 10,000 - 100,000 years. A blue giant is extremely bright. Like a lighthouse, they shine across a great distance. Even though blue giant stars are rare, they make up many of the stars we see at night because they shine so brightly. Blue giant stars die in a spectacular way. They grow larger just like the sun-sized stars, but then instead of shrinking and forming a planetary nebula, they explode in what is called a supernova. Supernova explosions can be brighter than an entire galaxy, and can be seen from very far away.

Giant Star Remember when we talked about sun-sized stars? We said that at the end of their lives these stars expand, taking up much more space than before. This is exactly what a Giant Star is. As a sun-sized star gets old, it starts to run out of its hydrogen fuel. When the process of burning hydrogen in the starâ&#x20AC;&#x2122;s core begins to slow down, the core gets more compact and dense. This means all the stuff in the middle of the star gets really close together. As the center gets smaller and smaller it starts to heat up again. When it gets hot enough it will start to burn a new fuel called helium. Once ignited, helium burns much hotter than hydrogen. The additional heat pushes the outer layer of the star out much further than it used to be, making the star much larger. Imagine a hot air balloon. As the air inside the balloon gets hotter, it stretches the balloon out further and further. As the giant star gets hotter, its outside stretches out further and further. When our own sun begins to stretch into a giant star, it will engulf Mercury, Venus, Earth and Mars.

Super Giantstar A super giant star is the exact same thing as a giant star only much bigger. Remember that as a star gets older it begins to run out of fuel. As the star runs out of fuel, it will start to burn out.

Just like the sun-sized stars, blue giant stars also begin to burn helium. As they do these stars get much hotter. This extra heat makes the outside of an old blue giant star stretch out further. Remember how hot air balloons stretch out as the air in them gets hotter? The only difference between Giant Stars and Super Giant Stars is their size. Super Giant Stars are much bigger. If the Sun were replaced by a super giant star, it would extend from the center of our Solar System almost all the way out to Uranus. Dead super giant stars/blue giant stars often turn into black holes. A black hole is a very compact object. Learn more about black holes How does this happen? As the star dies it explodes in a huge explosion called a supernova. The supernova blasts away most of the star. Anything left behind begins to fall into the middle of the star. It gets more and more compact, and smaller and smaller. If there is enough of the star left after the explosion, the star will be heavy enough to squash it down to the size of an atom, or even smaller.

BLACK H

LES

A black hole is a region of space from which nothing, not even light, can escape. 59

What are black holes? Have you ever had to vacuum your bedroom? When you do, watch closely because you will see the dirt and crumbs start to move towards the vacuum cleaner. A black hole is similar to a vacuum cleaner, cleaning up debris left behind in outer space. However, it is not suction power that makes things fall into a black hole. Suction would not be strong enough. Instead, a black hole uses the power of gravity to pull things towards it.

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How do black holes form? When a large star runs out of fuel it can no longer support its heavy weight. The pressure from the starâ&#x20AC;&#x2122;s massive layers of hydrogen press down forcing the star to get smaller and smaller and smaller. Eventually the star will get even smaller than an atom. Imagine that for a moment, an entire star squashed up into less space than a tiny atom. How can something get smaller but retain the same amount of mass, or stuff? It is really quite simple. If you take a sponge the size of a coke can, you can easily squish it in your hands until it is completely covered. But here is the interesting part. If you make something smaller by squishing it, its gravity becomes much stronger. Imagine then, if you squish a star into the size of an atom how powerful its gravity would become. A black holeâ&#x20AC;&#x2122;s gravity becomes so powerful that anything, including light that gets too close, gets pulled in. Thatâ&#x20AC;&#x2122;s right, not even light can escape the grasp of a black hole.

Anatomy of a Black Hole Black holes are made up of 3 main parts. The very outer layer of a black hole is called the Outer Event Horizon. Within the Outer Event Horizon you would still be able to escape from a black hole’s gravity because the gravity is not as strong here. The middle layer of a black hole is called the Inner Event Horizon. If you didn’t escape the black hole’s gravity before you entered the Inner Event Horizon, then you have missed your chance to escape. The gravity in this layer is much stronger and does not let go of objects it captures. At this point you would begin to fall towards the center of the black hole. The center of a black hole is called the Singularity. This is simply a big word that means squashed up star. The Singularity is where the black hole’s gravity is the strongest.

How can you fall into a black hole? Think of the Earth. When you are in outer space you can float around. If you get too close to the Earth you will be pulled in by its gravity. On the Earth, you could leave again in a rocket ship. However, if you fall into a black hole, there would be no way to get out because the gravity is so

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THE MOON

The English proper name for Earth’s natural satellite is “the Moon”. The noun moon derives from moone (around 1380), which developed from mone (1135), which derives from Old English,

The Moon is Earth’s only natural satellite and the fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary (though Charon, which orbits the dwarf planet Pluto, is proportionally larger), a quarter the diameter of Earth and 1⁄81 its mass. The Moon is the second densest satellite after Io. It is in synchronous rotation with Earth, always showing the same face; the near side is marked with dark volcanic maria among the bright ancient crustal highlands and prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a similar reflectance to coal. Its prominence in the sky and its regular cycle of phases have since ancient times made the Moon an important cultural influence on language, calendars, art and mythology. The Moon’s gravitational influence produces the ocean tides and the minute lengthening of the day. The

which humans have landed. While the Soviet Union’s Luna programme was the first to reach the Moon with unmanned spacecraft in 1959, the United States’ NASA Apollo program achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings between 1969 and 1972—the first being Apollo 11. These missions returned over 380 kg of lunar rocks, which have been used to develop a detailed geological understanding of the Moon’s origins (it is thought to have formed some 4.5 billion years ago in a giant impact event involving Earth), the formation of its internal structure, and its subsequent history.

Moon’s current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun, allowing it to cover the Sun nearly precisely in total solar eclipses.

These spacecraft have contributed to confirming the discovery of lunar water ice in permanently shadowed craters

The Moon is the only celestial body on 66

After the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft, notably by the final Soviet Lunokhod rover. Since 2004, Japan, China, India, the United States, and the European Space Agency have each sent lunar orbiters.

The Moon Phases The revolution of the Moon around the Earth makes the Moon appear as if it is changing shape in the sky. From Earth we see the Moon grow from a thin crescent to a full disk (or full moon) and then shrink back to a thin crescent again before vanishing for a few days.

The Moon phases are produced by the alignment of the Moon and the Sun in the sky.The lit part of the Moon always points the way to the Sun.What is the phase of the moon? The changing shape of the bright part of the Moon that we see is called its phase. What causes part of the Moon to be lit up? The moon is illuminated because it reflects the light from the sun. The part of the moon facing the sun is lit up. The part facing away from the sun is in darkness. What causes the different phases of the Moon? The phases of the Moon depend on its position in relation to the Sun and Earth. As the Moon makes its way around the Earth, we see the bright parts of the Moon’s surface at different angles. These are called “phases” of the Moon. What are the different phases of the Moon called? The phases of the moon work in a cycle starting with the new moon. Did you know? Countries near the equator see the crescent moon shaped like a smile?

The phases are named after how much of the moon we can see, and whether the amount visible is increasing, or decreasing each day.