M81 is without doubt one of the spiral wonders of the evening sky. It joins neighboring galaxy M82 to make one of the dynamic pairings of galaxies within the excessive northern heavens. At 12 million light-years distant, M81 is a major member of the M81 Group of galaxies — one of many nearest teams of galaxies to our personal Native Group. It is usually one of the distant objects within the universe accessible with out optical assist.
German astronomer Johann Elert Bode found this “nebulous patch” Dec. 31, 1774, calling it “roughly spherical, with a dense nucleus within the center.” Most observers following him hailed the brightness of the galaxy’s nucleus, together with Isaac Roberts, who photographed it and described it as a “spiral with a nucleus.” Certainly, M81 was the primary identified spiral galaxy to disclose proof of rotation.
M81 is just like the Milky Way, resembling a grand-design spiral with two arms. However these arms include spiral fragments that department into many secondary filaments. The arms additionally host a inhabitants of stars shaped in an episode of star formation that began about 600 million years in the past. That is proof that M81 could also be present process a surge of star formation alongside the spiral arms resulting from an in depth encounter with M82; the pair reached their closest factors about 300 million years in the past.
To search out M81, look about 2° east of 24 Ursae Majoris. When you stay below a darkish sky, use binoculars first to find the surprise, which shall be paired with M82 simply 38′ away. The telescopic view is splendid: An enormous indirect glow, concerning the obvious dimension of the Full Moon, shines forth with a pale-yellow gentle punctuated by a vivid stellarlike nucleus. Two Eleventh-magnitude stars burn simply south of the core and might simply be mistaken for supernovae. Satirically, in 1993, a supernova in M81 blazed to prominence simply west of those stars. At magnifications of 70–150x, the galaxy core transforms right into a misty spring of sunshine caressed by darkish vapors. Delicate wisps of spiral arms encompass the core, and collectively they appear to be a nonetheless {photograph} of the grandest rotating garden sprinkler within the cosmos.
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