Galaxy · Spiral
NGC 643B
NGC 643B is a galaxy in the direction of the constellation Hydrus, 186.9 million light-years away.
| Type | Spiral |
|---|---|
| Constellation | Hydrus |
| Distance | 186.9 million light-years (57.30 Mpc) |
| Diameter | 78,200 light-years · 0.89 × the Milky Way |
| Absolute magnitude | magnitude −20.81 |
| Apparent magnitude | magnitude 12.98 |
| Luminosity | 0.92 × the Milky Way |
| Right ascension (J2000) | 1h 39m 12.8s |
| Declination (J2000) | −75° 00′ 40″ |
| Source | 2MASS Redshift Survey (Huchra et al. 2012) |
In the sky
A telescope is needed to see it: its apparent magnitude is 12.98. Visible from the whole Southern Hemisphere and north to latitude 15° N. South of latitude 15° S it never sets.
Through a telescope from Earth
Light's journey
The light you see tonight set out 187 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 3,315.3 billion years.