WASP-17 is a newly discovered planet that is about 1,000 light years away from the earth in the constellation Scorpius. It revolves in the opposite direction of all the other known planets in the universe. The low-density WASP-17 was discovered by astronomers at the Keele University in Great Britain. The discovery of the planet, which is about twice the size of Jupiter, was announced on August 12, 2009.
via mahalo.com
"WASP-17 is about half the mass of Jupiter but bloated to twice its size. "This planet is only as dense as expanded polystyrene, 70 times less dense than the planet we're standing on," said professor Coel Hellier of Keele University.
The bloated planet can be explained by a highly elliptical orbit, which brings it close to the star and then far away. Like exaggerated tides on Earth, the tidal effects on WASP-17 heat and stretch the planet, the researchers suggest." Source: http://www.space.com/scienceastronomy/090812-backward-planet.html
