M47 is a bright, loose open cluster in Puppis that went missing for a long time because Messier recorded its position wrongly, until it was matched to a known cluster.
At a glance
| type | open star cluster |
|---|---|
| distance from the Sun | 1,530 light-years (468 pc) |
| its light left it | 1,530 years ago |
| size in the piece | about 14 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About M47
Messier listed M47 with a position that pointed to empty sky, and for a long time it was counted as missing. It was later recognised that a slip in his notes had moved it, and that M47 is the cluster William Herschel had independently catalogued, now NGC 2422.
The cluster is bright enough for the naked eye from a dark site and shows a scattering of hot blue-white stars in binoculars. It lies close on the sky to M46, a richer and much more distant cluster, so the two make a contrasting pair in one field.
What you see in the piece
From Earth it sits beside M46; fly out and the two separate, M47 the nearer by far.
Questions
How far away is M47?
M47 is about 1,530 light-years (468 pc) from the Sun.
Why was M47 lost?
Messier recorded its position with an error, so for a long time nothing was found there; it was later identified as the cluster NGC 2422.