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.

February 17, 1999
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

Hickson Compact Group 40
Credit: CISCO, Subaru 8.3-m Telescope, NAOJ

Explanation: Galaxies, like stars, frequently form groups. A group of galaxies is a system containing more than two galaxies but less than the tens or hundreds typically found in a cluster of galaxies. A most notable example is the Local Group of Galaxies, which houses over 30 galaxies including our Milky Way, Andromeda, and the Magellanic Clouds. Pictured above is nearby compact group Hickson 40. This group is located about 300 million light-years away toward the constellation of Hydra. Of the five prominent galaxies in Hickson 40, three are spirals, one is an elliptical and one is a lenticular. Many galaxies in compact groups are either slowly merging or gravitationally pulling each other apart.

Tomorrow's picture: Aerogel For Stardust

< Archive | Index | Search | Calendar | Glossary | Education | About APOD >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.