Astronomers have never liked the idea that our solar system--the sun and its family of nine planets--is the only one in the galaxy. They just couldn't imagine how one star could have planets and the other billions of stars have none.
So scientists have been searching through their telescopes for years, trying to find some evidence that other planets are circling around stars like the sun. Finally, last week they found one.
The newly discovered planet is orbiting a star called 51 Pegasus in the constellation named for the winged horse of Greek mythology. It is about 40 light-years, or a bit more than 235 trillion miles, from Earth-pretty close, in cosmic terms.
The discovery was first announced in early October by Swiss astronomers. It took a second sighting by Americans at Lick Observatory near San Jose, California, before scientists were convinced. They didn't actually see the planet, but they saw 51 Pegasus wobbling as the planet's gravity tugged on it.
Is there life on this distant planet? Probably not. Its huge size means it has crushing gravity. Also, it orbits so close to its parent star that the temperature is hotter than the hottest oven.
Still, there could be other planets circling 51 Pegasus, and maybe some are more hospitable to life. And who knows how many other stars have their own solar systems?
An Unearthly World
Not much is known about the new planet, but here are some ways it differs from our own.