Messier 81
Videos
Messier 81 is a grand design spiral galaxy about 12 million light-years away in the constellation Ursa Major. It has a D25 isophotal diameter of 29.44 kiloparsecs.
The HST's view of M81, with its open star clusters, globular star clusters, and regions of fluorescent gas.
An infrared image of Messier 81 taken by the Spitzer Space Telescope. The blue colors represent stellar emission observed at 3.6 μm. The green colors represent 8 μm emission originating primarily from polycyclic aromatic hydrocarbons in the interstellar medium. The red colors represent 24 μm emission originating from heated dust in the interstellar medium.
M81 (left) and M82 (right). M82 is one of two galaxies strongly influenced gravitationally by M81. The other, NGC 3077, is located off the top edge of this image.
M81 with satellite galaxy Holmberg IX, shown top center-right.
Nova
Videos
A nova is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star that slowly fades over weeks or months. All observed novae involve white dwarfs in close b
Artist's conception of a white dwarf, right, accreting hydrogen from the Roche lobe of its larger companion star
Nova Eridani 2009 (apparent magnitude ~8.4)
GK Persei: Nova of 1901
Nova in Andromeda Galaxy