Supernova
3C400.2 (SNR G53.6-2.2)
Supernova remnant
The shock wave of a supernova expanding at thousands of kilometres per second: it sweeps up and heats the interstellar gas and shines in radio waves. The distance is estimated from the radio surface-brightness–diameter (Σ–D) relation and may be off by a factor of two.
| Type | Supernova |
|---|---|
| Constellation | Sagitta |
| Distance | 6,590 pc (21.5 thousand ly) · estimated |
| Diameter | 189.8 ly |
| Type | Shell type |
| Radio flux (1 GHz) | 8 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 19h 38m 50.0s |
| Declination (J2000) | +17° 13′ 59″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 73° S. North of latitude 73° N it never sets. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 21 thousand years ago. At that time Homo sapiens was spreading out of Africa; there was no farming yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 381 million years.