M31 · Andromeda Galaxy
| Chinese name | 仙女座大星系 |
|---|---|
| Type | Galaxy |
| Constellation | And |
| RA | 00h43m |
| Dec | +41° |
| Apparent magnitude | 3.4ᵐ |
| Hemisphere | Northern |
| Best season | Autumn |
| Difficulty | Easy |
| Focal length | 短焦 135–400mm |
About
The Andromeda Galaxy lies about 2.5 million light-years away and is the nearest large spiral galaxy to the Milky Way, the most massive member of the Local Group, about 220,000 light-years across and spanning over 3° in the sky (roughly six Moon-widths). Its large apparent size, bright core and spiral arms reveal clear dust lanes and pink H II regions, accompanied by the dwarf elliptical satellites M32 and M110. It is approaching the Milky Way at about 110 km/s and is expected to begin merging with our Galaxy in roughly 4.5 billion years. One of the most distant objects visible to the naked eye, it fits a short focal length that captures the whole galaxy with its companions. It is the benchmark beginner galaxy and a classic subject for studying galactic structure.