8-micron image of the Spiral Galaxy Messier 81
Ssc2003 06d4

Credit: NASA/JPL-Caltech/K. Gordon (University of Arizona) & S. Willner (Harvard-Smithsonian Center for Astrophysics)

Observation • December 18th, 2003 • ssc2003-06d4

ssc2003-06d4

The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this image from NASA's Spitzer Space Telescope. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.

In this 8-micron image, emission is dominated by infrared light radiated by hot dust that has been heated by nearby luminous stars. Dust in the galaxy is bathed by ultraviolet and visible light from nearby stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles are composed of silicates (chemically similar to beach sand), carbonaceous grains and polycyclic aromatic hydrocarbons and trace the gas distribution in the galaxy. The well-mixed gas (which is best detected at radio wavelengths) and dust provide a reservoir of raw materials for future star formation.

About the Object

Name
Bode's GalaxyMessier 81M81NGC 3031UGC 5318
Type
Galaxy > Type > Spiral
Distance
12,000,000 Light Years
Redshift
-0.000113

Color Mapping

Band Wavelength Telescope
Infrared 3.6 µm Spitzer IRAC
Infrared 4.5 µm Spitzer IRAC
Infrared 5.8 µm Spitzer IRAC
Infrared 8.0 µm Spitzer IRAC
Infrared 24.0 µm Spitzer MIPS

Astrometrics

Position (J2000)
RA =9h 55m 34.0s
Dec = 69° 3' 54.9"
Field of View
23.5 x 17.9 arcminutes
Orientation
North is 268.7° left of vertical