APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
The Decade that Defined Star System
Explanation: As the 1990s began, the only planetary star system known was our own Solar System . The first extra-solar star system was discovered orbiting a pulsar in 1991. Slight changes in the precise arrival times of the pulses from the central small dense neutron star gave evidence of orbiting planets . By mid-decade Jupiter -like planets around Sun -like stars were being found by a slight wobble detected in the motion of these stars. Pictured above is an artist's sketch of a planet discovered orbiting HD217107 . As the decade comes to a close, over two dozen planetary star systems have been identified, one recently confirmed by the detection of a slight eclipse by the planet itself. An unambiguous discovery of Sun-like star systems containing Earth -like planets still remains a goal.
| Date | December 29, 1999 |
|---|---|
| Credit | Drawing Credit & Copyright: Lynette Cook |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |



