Planetary nebula
M 2-21
Planetary nebula
A shell of gas thrown off by a dying Sun-like star, glowing in the ultraviolet light of the hot core at its centre. Within a few tens of thousands of years it will disperse and fade from view. The distance is a statistical estimate, uncertain by 30–50 %.
| Type | Planetary nebula |
|---|---|
| Constellation | Sagittarius |
| Distance | 6,140 pc (20.0 thousand ly) · estimated |
| Diameter | 0.7 ly |
| Central star | V 14.7 |
| PN G name | PN G000.7-02.7 |
| Source | Strasbourg–ESO PN Catalogue |
| Right ascension (J2000) | 17h 58m 09.7s |
| Declination (J2000) | −29° 44′ 21″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 60° N. South of latitude 60° 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 20 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 355 million years.