Until 3 billion years ago, Mars was a wet planet much like Earth. It had land, an extensive atmosphere and an ocean that covered two thirds of the northern hemisphere as well as smaller bodies of water. But significant climate change caused the water and atmosphere to boil away, leaving Mars a dry and arid planet. Or so we thought… then came the news from Nasa – Water found on Mars!
Anything that is related to a sun is commonly described as being solar. Our sun is a typical medium-sized yellow star which is about 5 billion years old. Its surface temperature is about 5,500°C, but even that isn’t as hot as its superheated centre. Some parts of the sun’s surface are cooler, with a temperature of between 2,700–4,200°C, and these appear darker when viewed through specialised telescopes. These cooler patches are caused by fluctuations in the sun’s magnetism and are called sun spots.
