Nebula
W 51
H II region
A cloud of ionised hydrogen (H II region): a stellar nursery glowing in the ultraviolet light of the young, hot O and B stars inside it. The distance follows from the gas’s radial velocity and the Galaxy’s rotation curve (kinematic method).
| Type | Nebula |
|---|---|
| Constellation | Aquila |
| Distance | 5,320 pc (17.4 thousand ly) · estimated |
| Diameter | 48.5 ly |
| WISE name | G049.407-00.193 |
| Catalogue status | Known H II region |
| Source | WISE H II Catalog v3.0 |
| Right ascension (J2000) | 19h 22m 51.7s |
| Declination (J2000) | +14° 31′ 43″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 75° S. North of latitude 75° N it never sets. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 17 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 308 million years.