Star cluster
PTB 3
Open star cluster · 3.2 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 | Cepheus |
| Distance | 3,220 pc (10.5 thousand ly) |
| Age | 3.2 billion years |
| Member stars (MWSC) | 93 |
| Reddening E(B−V) | 0.50 |
| Source | MWSC (Kharchenko et al. 2013) |
| Right ascension (J2000) | 22h 13m 23.9s |
| Declination (J2000) | +70° 02′ 42″ |
In the sky
Visible from the whole Northern Hemisphere and south to latitude 20° S. North of latitude 20° N it never sets. It stands highest at midnight in August, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 11 thousand years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 186 million years.