Watching the Solar System from the Earth is one way of finding out about it. To learn more, people have used rockets to travel into space. There they have been able to look at parts of the Solar System more clearly. But although the first men landed on the Moon in 1969, no one has visited any of the planets. They are too far away and conditions are dangerous for humans.
However, as you have seen space probes – robot controlled unmanned spacecraft – have been sent far into the Solar System. The space probe Voyager 2 has travelled through the Solar System and is now well beyond the orbit of Pluto. As it travels it takes pictures and sends them back to Earth.
Voyager 2
This space probe gas already travelled across millions of kilometres of space, and has collected information on Jupiter, Saturn, Uranus and Neptune. The craft’s onboard computers are reprogrammed during its flight by electronic signals from Earth. The entire vehicle weighs only 815 kilograms. It carries equipment for 11 scientific experiments which are powered by a nuclear generator.
This is a photograph of the surface of Mars. The surface of Mars – you can see the solar panels of the lander at the bottom of the photo.