M67 in Cancer is a very old open star
cluster. It is believed to be between 4 and 8 billion years -
about the age of the solar system. Notice the preponderance of
"yellowish" stars and only a few blue stars. These red/yellow
stars have evolved into red giants.
h Persei. In contrast to M67
above, h Persei is very young - estimated to be only about 6
million years (1/1000 the age of M67). As a result the bright
stars are predominantly blue and extremely hot as compared to the red
stars of the much older M67.When this cluster was born, the dinosaurs on earth were long gone, mammals had appeared, and the first human-like creatures were starting to appear.