Star cluster
Alessi 18
Open star cluster · 1.0 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 | Puppis |
| Distance | 6,287 pc (20.5 thousand ly) |
| Age | 1.0 billion years |
| Member stars (MWSC) | 40 |
| Reddening E(B−V) | 0.65 |
| Source | MWSC (Kharchenko et al. 2013) |
| Right ascension (J2000) | 7h 37m 10.2s |
| Declination (J2000) | −26° 23′ 06″ |
In the sky
Visible from the whole Southern Hemisphere and north to latitude 64° N. South of latitude 64° 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 21 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 364 million years.