In 19 years of observations, the Hubble Space Telescope has amassed a huge archive of data--an archive that may contain the telltale glow of undiscovered extrasolar planets. Such is the case with HR 8799b, shown in this artist's concept. The planet is one of three extrasolar planets orbiting the young star HR 8799, which lies 130 light-years away. The planetary trio was originally discovered in images taken with the Keck and Gemini North telescopes in 2007 and 2008. But using a new image processing technique that suppresses the glare of the parent star, scientists found the telltale glow of the outermost planet in the system while studying Hubble archival data taken in 1998. The giant planet is young and hot, but still only 1/100,000th the brightness of its parent star. By comparison, Jupiter is one-billionth the brightness of our sun.åÊ

Image Credit: NASA, ESA, and G. Bacon (STScI)