Supernova
SNR G12.5+0.2
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 | Sagittarius |
| Distance | 15,000 pc (48.9 thousand ly) · estimated |
| Diameter | 77.6 ly |
| Type | Composite (shell + pulsar wind nebula) ? |
| Radio flux (1 GHz) | 0.6 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 18h 12m 14.0s |
| Declination (J2000) | −17° 55′ 00″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 72° N. South of latitude 72° 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 49 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 868 million years.