Nebula
Sh2-187
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 | Cassiopeia |
| Distance | 812 pc (2.6 thousand ly) · estimated |
| Diameter | 15.4 ly |
| WISE name | G126.664-00.801 |
| Catalogue status | Known H II region |
| Source | WISE H II Catalog v3.0 |
| Right ascension (J2000) | 1h 23m 08.8s |
| Declination (J2000) | +61° 50′ 28″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 28° S. North of latitude 28° 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 around 623 BC. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 47 million years.