Open cluster in Auriga
M36
The youngest of the three clusters strung across Auriga at about 25 million years — too young for anything in it to have reddened. Everything you can see is still blue. It holds about sixty stars, none of them evolved off the main sequence, in a space perhaps fourteen light-years across.
That is the whole of its interest and it is not a small one: this is what M37 looked like before anything in it aged, and the two sit four degrees apart for the comparison.
- Catalogue
- M36
- Type
- Open cluster
- Constellation
- Auriga
- Distance
- 4,100 light-years
- Apparent magnitude
- 6.3
- Surface brightness
- 20.3 mag/□″
- Apparent size
- 12′
- Right ascension
- 5h 36m
- Declination
- +34.13°
- Found by
- Giovanni Batista Hodierna, before 1654
Magnitude 6.3 for the cluster as a whole, though that is a sum rather than a thing you see: what reaches you is a scatter of separate stars, and whether you catch it depends on how bright the brightest of them are. Why surface brightness is the number that matters.
Could you see it?
Straightforward with the naked eye from Bortle 3 or darker; with 10×50 binoculars from Bortle 9.
| Sky | Eye | 10×50 | 80mm | 130mm | 200mm |
|---|---|---|---|---|---|
| Bortle 1 21.9 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 2 21.7 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 3 21.4 mag/□″ | Easy | Easy | Easy | Easy | Easy |
| Bortle 4 20.9 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 5 20.3 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 6 19.3 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 7 18.6 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 8 18.1 mag/□″ | No | Easy | Easy | Easy | Easy |
| Bortle 9 17.8 mag/□″ | No | Easy | Easy | Easy | Easy |
At the eyepiece
The sparsest of the Auriga three and the quickest to look at — sixty-odd blue-white stars with no reddening anywhere in it. In the same session as M37 it comes off second best, which is not its fault and is the way most people meet it.
When, and from where
Highest in the middle of the night in December. Passes overhead at 34°N and rises from everywhere except the far south — below 56°S it never clears the horizon.
| Latitude | Highest it gets | |
|---|---|---|
| 60°N Oslo, Anchorage | 64° | Never sets |
| 51°N London, Calgary | 73° | |
| 40°N New York, Madrid | 84° | |
| 30°N Cairo, Houston | 86° | |
| 0°N the equator | 56° | |
| 33°S Sydney, Cape Town | 23° |
Nearby in the sky
The whole catalogue →2 more of the catalogue sit within five degrees, close enough to take in on the same night without moving far. Everything below is measured from M36 itself, not from the middle of Auriga.
- M38 Open cluster 2.3° apart Auriga · magnitude 7.4 · binoculars from Bortle 9 or darker
- M37 Open cluster 3.8° apart Auriga · magnitude 6.2 · binoculars from Bortle 9 or darker
- M1 Crab Nebula 12° apart Taurus · magnitude 8.4 · binoculars from Bortle 5 or darker
- M35 Open cluster 12° apart Gemini · magnitude 5.3 · binoculars from Bortle 9 or darker
Terms on this page
- The main sequence The long, stable middle age a star spends fusing hydrogen in its core.
One of 110. Positions J2000; the sky is the final authority.