Supernova
SNR G21.5-0.9
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.
| Type | Supernova |
|---|---|
| Constellation | Scutum |
| Distance | 4,800 pc (15.7 thousand ly) |
| Diameter | 22.8 ly |
| Type | Composite (shell + pulsar wind nebula) |
| Radio flux (1 GHz) | 7 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 18h 33m 33.0s |
| Declination (J2000) | −10° 34′ 59″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 79° N. South of latitude 79° S it never sets. It stands highest at midnight in June, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 16 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 278 million years.