Super Stars Written by Jenny Vaughan
Contents Stargazing Radio waves in space The nearest stars Little star, big star Star factories What happens inside a star? When small stars die When large stars die Recycled stars Naming the stars Constellations Star quest Glossary Index The life and death of stars
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Stargazing For thousands of years, people have been looking up at the sky. As they looked, they wondered about the millions of dots of light they could see there. What could they be? How did they get there? How far away were they? What they saw were stars and planets. Although they didn’t really know what these were, they saw that they formed patterns, and they knew where to find these patterns in the sky.
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Telescopes Long ago, the only way people could see stars and planets was with the naked eye. But when telescopes were invented, around 500 years ago, everything changed. When anyone looked through a telescope, they could see far-away objects very clearly. Galileo Galilei was an astronomer who lived in Italy between 1564–1642. He was one of the first scientists to point a telescope at the sky to study stars and planets. Using a telescope, it was possible for Galileo and others to see stars and planets better than before, and to make new discoveries. For thousands of years, people had thought the Earth was in the centre of the universe, and the Sun, Moon, planets and stars surrounded it. Looking through a telescope, Galileo realised that the Earth is just one planet in orbit around a single star – the Sun. Beyond that, there’s more space, and more stars than we can count.
Galileo Galilei
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Jupiter and its moons
Saturn
Mars
Mercury
Sun Venus
Moon Earth
This is how Galileo saw the universe. The Sun is in the centre and the planets orbit around it.
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The biggest telescope on Earth Astronomers today still use telescopes, but many of them are much bigger and more powerful than the one Galileo used. The telescopes are built in places like the top of mountains, where the air is very clear and clean. From there, experts can get the best view of the stars with no pollution to get in the way. The clear, clean mountain air means the telescope can get the best picture possible.
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This is what the telescope will look like when it’s finished.
The biggest ever telescope on Earth is being built in the Atacama Desert, Chile. It’s called the European Extremely Large Telescope, or E-ELT. The E-ELT will give astronomers a better view of the stars and planets from Earth than ever before.
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Telescopes in space There are also telescopes in space, orbiting Earth. The Hubble Space Telescope has been working in space for over 20 years. It can see further than the telescopes on Earth, and it sends back clear pictures of the stars to scientists on the ground. the Hubble Space Telescope
Star fact The Hubble Space Telescope travels around the Earth at 7.5 kilometres per second!
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Soon, a new telescope will be launched into space. The James Webb Space Telescope is the size of a tennis court! It won’t orbit the Earth, like the Hubble Telescope. Instead, it’ll orbit the Sun. This telescope will be able to see further and better than the Hubble Space Telescope, and tell scientists much more
Star fact Stars in space are in enormous groups called galaxies. The Sun, Earth and all the planets are in a galaxy called the Milky Way. Powerful telescopes can spot other galaxies, far beyond the Milky Way.
about the universe. the James Webb Space Telescope
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Radio waves in space Stars beam out light, and that’s what we see from Earth. But they also send out invisible radio waves. These are waves of energy that travel through space. Special telescopes called radio telescopes pick these up. They are like radios, which pick up radio waves from radio stations, and turn these into sound. A radio telescope turns the radio waves from space into signals and sends these to a computer. The computer uses the signals to make a picture of whatever is sending the radio waves. A huge radio telescope. This one is at a place called Jodrell Bank, in England.
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Radio telescopes can tell scientists a lot about what’s happening in space that no one can see with an ordinary telescope. These include distant stars, which don’t give off enough light to be seen. dish picking up signals
image
computer
This is the centre of the Milky Way galaxy, seen using a radio telescope.
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