M38 was discovered by Giovanni Batista Hodierna before 1654. Charles Messier included it in his catalog on September 25, 1764
M38 (The Starfish Cluster) is the open cluster of stars in the upper part of the image above. The cluster formed about 220 million years ago. It lies in the constellation of Auriga at a distance of approximately 4,200 light years. The cluster has a diameter of about 25 light years and, as viewed from Earth, is about two-thirds the size of the full Moon. The brightest star in the cluster is a 7.9 magnitude type GO yellow supergiant. Type G stars have a surface temperature of 5,000 to 6,000 degrees. In comparison to our own Sun, this supergiant star in M38 shines 900 times brighter.
Located below M38 is the smaller open cluster designated NGC 1907. It is comprised of about 30 relative bright stars. It lies approximately 4,500 light years from the Earth. Research has determined that the two clusters did not form in the same part of the galaxy and that NGC 1907 and M38 are just flying past each other. At any rate, the proximity of these clusters to each other makes an impressive celestial portrait.