M31 - Andromeda Galaxy
 
Date:
 
October 26, 2013
 
Location:
 
Deerlick Astronomy Village
Sharon, Georgia USA
Telescope:
 
Orion ED80 Apo
 
Camera:
 
Canon 450D DSLR
 
Mount:
 
Orion Atlas EQ-G
 
Acquisition:
 
Nebulosity
 
Filters:
 
None
 
Total Integration:
 
40 minutes
Subexposures:
 
20 x 120s @ ISO 1600
 
Calibration:
 
None
 
The Andromeda Galaxy, also known as M31 or NGC 224, is a spiral galaxy approximately 2.5 million light-years from Earth. It is the nearest major galaxy to the Milky Way and was often referred to as the Great Andromeda Nebula in older texts. It received its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. Being approximately 220,000 light years across, it is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 44 other smaller galaxies.

Measurements made by the Spitzer Space Telescope have revealed that the Andromeda Galaxy contains one trillion stars, at least twice the number of stars in the Milky Way, which is estimated to be 200–400 billion.

The Milky Way and Andromeda are expected to collide in 3.75 billion years, eventually merging to form a giant elliptical galaxy or perhaps a large disc galaxy.

The Andromeda Galaxy, at apparent magnitude 3.4, is one of the brightest of any of the Messier objects. It is visible to the naked eye on moonless nights even when viewed from moderately light polluted areas. Although it appears more than six times as wide as the full moon when photographed, only the bright central region is visible to the naked eye or when viewed using binoculars or a small telescope.