Supernova
Milne 56 (SNR G5.4-1.2)
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 | 3,460 pc (11.3 thousand ly) · estimated |
| Diameter | 114.8 ly |
| Type | Composite (shell + pulsar wind nebula) ? |
| Radio flux (1 GHz) | 35 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 18h 02m 10.0s |
| Declination (J2000) | −24° 53′ 59″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 65° N. South of latitude 65° 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 11 thousand years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 200 million years.