The Sun, Moon and Planets

The SUN, MOON and PLANETS

Which matters most? Welcome to space- or at least, the tiny bit you live in. I'm a comet called Edmond. My journeys take me all around this area, so I know all the planets around the Sun. Rocky planets are those with a surface made of solid material. Gas giant and ice giant planets are made mostly of huge balls of fluid. The Sun and the planets all think they're important. For Earthlings, the Moon is also important. But which is the MOST important? Let's ask them and try to find out...

The Sun The big, hot one I contain 99.9% of all the matter in the solar system! That gives me the strongest gravity around. If I wasn't keeping them here, the planets would go pinging off who knows where. Earth could end up being sucked into a black hole... ...or drifting into a field of asteroids. Without my heat and light, life on Earth would not be possible. Plants would not grow. Animals that eat plants could not survive. Humans would not have anything to eat. It would also be very, very cold. I hold the solar system together and provide the warmth that makes life on Earth possible. I MUST matter most.

Mercury Hot... and cold Earth- foo! Earth takes a YEAR to orbit the Sun. I've done it four times by then! That's not the only thing about me that's different from Earth. Each day and night on me lasts nearly 59 Earth days. Imagine having to go to bed for half that! Goodnight listeners and see you in 29 days time. The Sun is so close that when it comes up, I get very, very hot. Inside temperature: 20°C Outside temperature: 450°C At least, it's hot at the surface. Most of the heat quickly escapes into space. At night, the sunshine disappears and suddenly it's MINUS 180°C. This is a very strange place. I'm never going there again! So, I THOUGHT I was pretty important- but it turns out that if you're from Earth, you might not agree.

Venus Greenhouse gone wrong This is so exciting! I'm in a book! It's making me feel all hot and bothered! People sometimes call me 'Earth's twin'- and it's true because... ...we're almost the same size and we both have mountains and volcanoes on the surface. We're not THAT alike, though. My thick atmosphere traps a lot more heat from the Sun- making me the solar system's hottest planet. My atmosphere is not very welcoming to humans. Venus's greenhouse effect. Sun's heat Layers of gas Heat trapped Even though they wouldn't like it here, I still matter to Earthlings. I show them what can happen when a greenhouse effect gets out of control! Atmosphere of Venus (not very welcoming) Space Mist of sulphuric acid drops (poisonous) More sulphuric acid mist (more poisonous) Sulphuric acid drops and dust (poisonous) Carbon dioxide (poisonous)

Earth Home Obviously I'm the most important planet, because I'm where you live! I'm the right distance from the Sun for it to be warm, but not too hot. Surface temperature 5,500°C Everything about me is just perfect for humans (and other living things, too). There is a surface to stand on, unlike the gas giant planets (on pages 18-25). Sunlight travels through space to Earth Average temperature 14.74°C There's air to breathe and plenty of water (unlike any of the other planets). Sometimes too much water... I like it! Me too. The only problem is that I'm getting hotter. The more greenhouse gases humans release, the hotter I get. The extra heat is causing all sorts of problems, like floods and droughts.