This makes it one of the oldest open clusters currently known.
M46 and M47 are two open clusters in the same binocular field.
It is considered to be one of the more inconspicuous open clusters.
The outskirts of the galaxy have many young open clusters.
Only open clusters are near enough for this technique to be useful.
At the time of the discovery it was the only known planet in an open cluster.
This open cluster is particularly ancient, estimated to be nearly one billion years old.
He continued this work on open clusters for the next twenty years.
There are over 1,000 known open clusters in our galaxy, but the true total may be up to ten times higher than that.
The older open clusters tend to contain more yellow stars.