Nexus Research Group - The Solar System

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The Sun is a star called Sol. It is mostly made up of a cloud of Hydrogen gas. It is a medium sized star about 5 billion years old. In the centre of the Sun, Hydrogen atoms fuse to form Helium where the temperature is 14 million degrees. The surface temperature is much "colder", only about 5,500 degrees. Different parts of the Sun rotate at different rates. The equator spins fastest, taking 25 days for one rotation. The polar regions can take around 35 days. The strong pull of gravity from the Sun is what keeps the planets from wandering off into deep space.

Mercury is made of rock and completes one orbit of the Sun in only 88 days. It is only 58 million kilometres from the Sun and its surface is so hot that lead and tin metal would melt. Mercury has no moons and no breathable atmosphere. The thin atmosphere it does have is mainly sodium from the baking hot rocks.

Venus is made of rock and completes one orbit of the Sun in 224.7 days. It is 108 million kilometres from the Sun. Venus has no moons. It is covered in thick clouds that rain sulphuric acid and the pressure at the surface is a crushing 95 times greater than here on Earth. The clouds reflect light back to us and we sometimes call this bright sky object the "Evening Star". The clouds also keep in the heat that comes from the Sun, in a similar way to that of the "greenhouse effect". It is about 480 degrees at the surface, and covered with volcanoes.

Earth is the planet we live on, the only planet with breathable air and drinkable water. Earth is made of rock and completes one orbit of the Sun in 365.24 days. It is 150 million kilometres from the Sun and has one moon. Its surface is covered mostly by seas and the planet has many forms of life. The atmosphere is made up mostly of Nitrogen gas, with Carbon Dioxide and Oxygen making up the important gases for life to continue. If too much Carbon Dioxide builds up from pollution, such as burning petrol and other fuels, some people think that Earth may become like Venus. The moon, which is about 1/4 the mass of the Earth, is slowly moving away and may one day escape the pull of the Earth to wander into space.

Mars is made of rock and completes one orbit of the Sun in 687 days. It is 228 million kilometres from the Sun and its surface is covered in a form of iron rust. This is why some call it the "Red Planet". Mars has 2 moons, Phobos and Deimos. Because Mars is smaller than Earth, it has a weaker pull of gravity, so you would weigh only two-fifths your weight. The thin atmosphere is cold and made up of Carbon Dioxide with a little Oxygen and water. At the equator the temperature is about 0 degrees, at the poles it is -150, cold enough to freeze the Carbon Dioxide into "dry-ice". It has been suggested that we could melt this and provide an atmosphere to grow plants which would in turn produce oxygen - we could then live on Mars...

Jupiter is the largest planet, 318 times more massive than the Earth. It takes about 12 years to orbit the Sun and is 773 million kilometres away. It is a huge ball of gas, all the other planets together are still not as big as Jupiter. It has a faint ring around it and Jupiter's surface is made up of belts of colourful clouds. There is a Great Red Spot, a huge "hurricane" that can be seen through telescopes on Earth. Jupiter rotates once in 10 hours, so fast it bulges a little at the equator. It is almost a star, made up of Hydrogen and a little Helium, and emitting more energy than it receives from the Sun. Jupiter has at least 16 moons, the four largest are Io, Ganymede (bigger than Mercury), Callisto and Europa.

Saturn is made of gas and completes one orbit of the Sun in 29 years. It is 1.4 billion kilometres from the Sun and is would float on water if you found a swimming pool big enough! Saturn has a colourful ring system made up of water ice or ice covered bits of rock. Saturn has many moons but the biggest, Titan, is unusual because it has an atmosphere.

Uranus is mainly made up of hydrogen and helium but a little methane gives Uranus a blue color. It has a rocky core and completes one orbit of the Sun in 84 years. It is 2.86 billion kilometres from the Sun and it has a thin ring system. Uranus is very cold and it is unusual because it rotates "on its side". Some people think that a long time ago, Uranus collided with another large planet and toppled over. Uranus has five large moons and 10 tiny moonlets.. Some people think

Neptune completes one orbit of the Sun in 165 years. It is 4.5 billion kilometres from the Sun and it has a thin ring system. Neptune is actually warmer than Uranus because it has internal heat, giving off three times as much as the heat it receives from the Sun. Neptune has a Great Dark Spot, similar the the spot in the atmosphere of Jupiter. Triton, one of the moons of Neptune, is bigger than Earths moon.

Pluto is sometimes closer to the Sun than Neptune due to the shape of its orbit about the Sun. Pluto is closest to the Sun at 4.2 billion kilometres and furthest away at 7 billion kilometres. Pluto is the smallest planet in the solar system. Scientists have discovered six other "bodies" after Pluto. They are very small so are not called planets yet. The first two are named Smiley and Karla.

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