Simran Singh, of Corran School, asks :-
Is there any evidence that another solar system exists suitable to support human life as we know it?
Karen Pollard, an astronomer at the University of Canterbury, responded.
To support life as we know it, a planet would need to be similar in size and temperature to the Earth and, to allow life to evolve on its surface, would need to be solid (and not a gas planet like Jupiter, Saturn, Neptune or Uranus).
The most successful planet-hunting technique involves searching for 'wobbles' in the motion of a star. When a planet orbits around a star, the gravitational force between them causes the star to be pulled around in a small circle: the star appears to `wobble' in space. This `wobble' tells us there is a planet present, even if we can't see the planet directly.
Using this technique astronomers have so far found nine stars that have planets about the size of Jupiter orbiting around them. Because these are all Jupiter-size planets, astronomers believe it is very unlikely that they could support life. Also, most of them are much closer to their stars than the Earth is to the Sun so would be too hot.
The fact that astronomers have now found nine new planetary systems suggests that planets are common throughout the cosmos. This raises our hopes that there are Earth-like planets out there that can support life, but we still don't have any real evidence yet. In the future astronomers hope to make more sophisticated instruments and use improved techniques to find these Earth-sized planets.