Star cluster
Ruprecht 171
Open star cluster · 3.5 billion years
An open cluster of stars born together from the same gas cloud in the Milky Way’s disc; the Galaxy’s tidal forces will disperse it within a few hundred million years. Position, distance, age and member count come from the MWSC catalogue; the total brightness is roughly estimated from the member count.
| Type | Star cluster |
|---|---|
| Constellation | Sagittarius |
| Distance | 1,159 pc (3.8 thousand ly) |
| Age | 3.5 billion years |
| Member stars (MWSC) | 66 |
| Reddening E(B−V) | 0.25 |
| Source | MWSC (Kharchenko et al. 2013) |
| Right ascension (J2000) | 18h 32m 06.0s |
| Declination (J2000) | −16° 00′ 36″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 74° N. South of latitude 74° 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 around 1755 BC. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 67 million years.