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.
M81 in True Color
Explanation: Here's what a spiral galaxy REALLY looks like. Yesterday, M81 was shown in two colors only, but here we see M81 at its most colorful . In the above picture , note how blue the spiral arms are - this indicates the presence of hot young stars and on-going star formation . Also note the yellow hue of the nucleus, possibly designating a population of older stars many billions of years old. M81 is actually a dominant member of a group of galaxies which includes M82 and several other galaxies. Unlike our Local Group of galaxies, large galaxies in the M81 group are actually colliding . It is possible that M81's interaction with M82 create the density waves which generate M81's spiral structure.
| Date | July 14, 1996 |
|---|---|
| Credit | Credit: Gregory Bothun (U. Oregon), Courtesy Bill Keel (U. Alabama) |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |