M46 is a rich open cluster in Puppis, a dense field of faint stars with a small planetary nebula, NGC 2438, apparently set in its edge by chance alignment.
At a glance
| type | open star cluster |
|---|---|
| distance from the Sun | 5,070 light-years (1.55 kpc) |
| its light left it | 5,070 years ago |
| size in the piece | about 31 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 M46
M46 is an open cluster in Puppis, in the winter Milky Way, catalogued by Charles Messier. It is rich and fairly evenly packed, a hazy patch in binoculars that a telescope resolves into a great many stars of similar brightness. Close beside it in the sky lies M47, sparser and brighter, but nearer the Sun; the two make a pleasing pair in a wide field.
M46 is considerably older than M47. Its brightest stars are no longer the hottest blue giants, which have already died, and the cluster’s light is dominated by longer-lived stars. The planetary nebula NGC 2438 appears near its northern edge, but its distance and velocity show it is a foreground object, not a cluster member.
What you see in the piece
Fly to it and the planetary nebula that looked set among its stars from Earth peels away towards the Sun, leaving the cluster behind.
Questions
Is the Ring-like nebula in M46 part of the cluster?
No. The planetary nebula seen in front of M46 is closer to the Sun and moves differently; the overlap is a chance alignment. M46 itself is 5,070 light-years (1.55 kpc) from the Sun.