Deep Sky

Open cluster
Constellation Gemini
This is considered a galactic cluster of around 200 stars.  They are some 2,800 light-years from earth.  Easily seen with a the naked eye, they appear as a young cluster, approx 110 – 150 million years, note the number of blue, blue-white stars in this cluster compared to the cluster below them them.  They are some 24 light-years in diameter.   Notice the difference compared to NGC 2158, an older and more compact open cluster.  This cluster is over four times farther away, some 10 times older, and as I said earlier a lot more compact.  The blue ‘fast burners’ are gone now leaving the more mature and older yellow starts to carry on.

10 images
20 second
23 Mar 12