Star cluster
Ruprecht 31
Open star cluster · 447 million 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 | Puppis |
| Distance | 541 pc (1.8 thousand ly) |
| Age | 447 million years |
| Member stars (MWSC) | 27 |
| Reddening E(B−V) | 0.10 |
| Source | MWSC (Kharchenko et al. 2013) |
| Right ascension (J2000) | 7h 42m 59.4s |
| Declination (J2000) | −35° 35′ 35″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 54° N. South of latitude 54° S it never sets. It stands highest at midnight in January, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 261. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 31 million years.