National Trust: Out and About Sky Explorer: A children’s guide to clouds, constellations and other a

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OUT AND ABOUT

A children’s guide to clouds, constellations and other amazing things to spot in the sky

CONTENTS 4–5 Introduction 6–7 Where does the sky begin? 8–9 Why is the sky blue? 10–11 The sky by day 12–13 Sky-spotting in the daytime 14–15 Clouds 16–17 Types of cloud 18–21 Low clouds 22–25 Medium clouds 26–27 High clouds 28–29 Cloud spotter ID quiz 30–31 Planes and contrails 32–33 Keep a cloud diary 34–35 Sunrise and sunset 36–37 Solar eclipses 38–39 Make your own eclipse viewer 40–41 Rainbows 42–43 Make a rainbow 44–45 Mirages 46–47 The sky by night 48–49 Sky-spotting at night 50–51 What is a star? 52–57 Constellations 58–59 Invent your own constellation 60–61 Star or planet? 62-63 Satellites and the ISS 64–65 Steer by the stars 66–67 The moon 66–69 Lunar eclipses 70–71 Thunder and lightning 72–73 Make your own lighting 74–75 The northern lights 76–77 Quiz 78–79 Glossary 80 Index

WHERE DOES THE SKY BEGIN?

Take a look up, past the tops of the trees and the roofs of the houses. The sky seems to go on, up and up, forever! But what is the sky, and where does it begin?

Our planet, Earth, is surrounded by a layer of gases called the atmosphere.

These gases are held in place by the planet’s gravity, and they help make life on Earth possible.

The atmosphere gives us the oxygen we need to breathe and protects us against dangerous radiation that comes from the sun. It also acts like a blanket, trapping heat from the sun’s rays and keeping Earth’s surface warm enough for us to survive. This is called ‘the Greenhouse Effect’.

So when you look up into the sky, you are looking up into this clear mix of gases called the atmosphere that starts at the Earth’s surface. Really, the sky is all around you!

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EXOSPHERE (600 – 10,000 km)

THERMOSPHERE (85-600 km)

International Space Station (page 64)

The

MESOSPHERE (50 to 85 km)

Spacecraft Satellites (page 64)

International Space station to be added

Satellites (page 64)

The Northern Lights (page 74)

Meteors

STRATOSPHERE (14.5 to 50 km)

Jet planes (page 32)

TROPOSPHERE (up to 14.5 km)

Storms (page 70)

Clouds (page 14)

Light aircraft

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Karman Line (outer space begins here)

WHY IS THE SKY BLUE?

The gases that make up our atmosphere are colourless, but on a clear day the sky is a beautiful blue. You may have heard some people say this is caused by the way light reflects off the ocean, or by water droplets in the atmosphere, but the truth is it’s all down to the sunlight!

The white light that human eyes can see is made up of seven different colours – red, orange, yellow, green, blue, indigo and violet – even though normally we don’t see them all separately.

Light moves in waves. The longer waves make light that is more red, and the shorter waves make light that is more blue. Together, all these waves make up white light.

VIOLET INDIGO BLUE GREEN YELLOW ORANGE RED

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When rays of white light from the sun reach the Earth, they hit the tiny particles of gas and dust in the atmosphere, which scatter (or split) the light into its different colours. The shorter blue waves of light are scattered much more than the longer red ones.

This means that when we look up, our eyes see a lot more of the blue light than red light, making the sky a bright blue.

This is called ‘Rayleigh scattering’, named after the scientist Lord Rayleigh who discovered it.

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THE SKY BY DAY

Rise and shine! The sun is up and a new day has come. There’s so much to see in the sky – whatever the weather.

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