Nebula
Sh2-170
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 | 4,720 pc (15.4 thousand ly) · estimated |
| Diameter | 118.7 ly |
| WISE name | G117.639+02.275 |
| Catalogue status | Known H II region |
| Source | WISE H II Catalog v3.0 |
| Right ascension (J2000) | 0h 01m 44.1s |
| Declination (J2000) | +64° 38′ 07″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 25° S. North of latitude 25° N it never sets. It stands highest at midnight in September, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 15 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 273 million years.