Galaxy · Spiral
NGC 21
NGC 21 is a galaxy in the direction of the constellation Andromeda, 222.2 million light-years away.
| Type | Spiral |
|---|---|
| Constellation | Andromeda |
| Distance | 222.2 million light-years (68.14 Mpc) |
| Diameter | 95,800 light-years · 1.1 × the Milky Way |
| Absolute magnitude | magnitude −20.95 |
| Apparent magnitude | magnitude 13.22 |
| Luminosity | 1 × the Milky Way |
| Right ascension (J2000) | 0h 10m 46.9s |
| Declination (J2000) | +33° 21′ 10″ |
| Source | 2MASS Redshift Survey (Huchra et al. 2012) |
In the sky
A telescope is needed to see it: its apparent magnitude is 13.22. Visible from the whole Northern Hemisphere and south to latitude 57° S. North of latitude 57° N it never sets. It stands highest at midnight in September, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 222 million years ago. At that time dinosaurs ruled the Earth. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 3,942.4 billion years.