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.

2004 April 7
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Unusual Spiral Galaxy M66
Credit & Copyright: Canada-France-Hawaii Telescope, J.-C. Cuillandre (CFHT), Coelum

Explanation: Why isn't spiral galaxy M66 symmetric? Usually density waves of gas, dust, and newly formed stars circle a spiral galaxy's center and create a nearly symmetric galaxy. The differences between M66's spiral arms and the apparent displacement of its nucleus are all likely caused by the tidal gravitational pull of nearby galaxy neighbor M65. Spiral galaxy M66, pictured above, spans about 100,000 light years, lies about 35 million light years distant, and is the largest galaxy in a group including M65 and NGC 3628 known as the Leo Triplet. Like many spiral galaxies, the long and intricate dust lanes of M66 are seen intertwined with the bright stars and nebulas that light up the spiral arms.

Tomorrow's picture: elusive jellyfish

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

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.