Supernova
HB3 (SNR G132.7+1.3)
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 | Cassiopeia |
| Distance | 2,730 pc (8.9 thousand ly) · estimated |
| Diameter | 207.4 ly |
| Type | Shell type |
| Radio flux (1 GHz) | 45 Jy |
| Source | Green's SNR Catalogue |
| Right ascension (J2000) | 2h 17m 40.0s |
| Declination (J2000) | +62° 45′ 00″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 27° S. North of latitude 27° N it never sets. It stands highest at midnight in October, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 8,904 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 158 million years.