An infrared view of the M81 Galaxy by NASA.

The M81 Galaxy is located 12 million light-years from our Milky Way, located in the northern constellations of Ursa Major, including the Big Dipper, the galaxy Messier 81 is easily visible by large telescopes and small telescopes. 

Friends As we know, NASA launched the Spitzer Space Telescope in August 2003, a few days after its launch, the Spitzer Space Telescope released the public, M81 being one of its first datasets. Nasa Spitzer  On the occasion of the 16th anniversary of the Space Telescope, the image, taken by Spitzer, is on one occasion the new image, with expanded observations and improved processing,Hu is shown again.

This Spitzer Space Telescope features a combined mosaic of infrared array camera (IRAC) data at wavelengths of 3.6 / 4.5 μm (blue / cyan) and 8 μm (green) with Infrared Image Photometer (MIPS) data at 24 μm is.  And it detects a distribution of 3.6-micron near-infrared data (blue) stars, though the same Spitzer space telescope obscured image dust as unaffected, and the m81 galaxy with a relatively small size of spiral arms, a  Very smooth stellar mass distribution is revealed.

As one moves toward longer wavelengths, these predominantly spiral arms become the dominant feature of the galaxy. And the same 8-micron emission (green) is dominated by infrared light, dispersed by hot dust, which is due to  There is hot dust by the bright stars near it. 

Near the dust of stars in the galaxy is bathed by ultraviolet and visible light, and by absorbing the same ultraviolet or several visible-light photons, a dust grain is heated, and it is, for a long time, infrared  Re-emits energy at wavelengths.  Dust particles in the galaxy are formed by silicates (chemically similar to beach sand), carbonaceous grains, and polycyclic aromatic hydrocarbons, and they detect gas distribution in the galaxy.