The Hubble Space Telescope, in collaboration with ground-based observatories, has given definitive evidence for the existence of the nearest extrasolar planet to our solar system:
The Jupiter-sized world orbits the Sun-like star Epsilon Eridani, which is only 10.5 light-years away (approximately 63 trillion miles). The planet is so close it may be observable by Hubble and large ground-based telescopes in late 2007, when the planet makes its closest approach to Epsilon Eridani during its 6.9-year orbit.
The Hubble observations were achieved by a team led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas at Austin. The observations reveal the the planet's true mass, which the team has calculated to be 1.5 times Jupiter's mass.
Hubble also found that the planet's orbit is tilted 30 degrees to our line of sight, which is the same inclination as a disk of dust and gas that also encircles Epsilon Eridani. This is a particularly exciting result because, although it has long been inferred that planets form from such disks, this is the first time that the two objects have been observed around the same star.
The research team emphasized that the alignment of the planet's orbit with the dust disk provides compelling direct evidence that planets form from disks of gas and dust debris around stars.