Supernova
SNR G4.2-3.5
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 | 9,810 pc (32.0 thousand ly) · estimated |
| Diameter | 260.3 ly |
| Type | Shell type |
| Radio flux (1 GHz) | 3.2 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 18h 08m 55.0s |
| Declination (J2000) | −27° 03′ 00″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 63° N. South of latitude 63° 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 32 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 568 million years.