High in the winter sky, the Pleiades look like a tiny dipper. Those with sharp eyes can see seven stars in the open star cluster M45, or the Seven Sisters. Some people report seeing up to 14 stars under the best conditions. But most, including myself, can see six at best. In this image from NASA’s Hubble Space Telescope, we see hundreds of stars.
Ancient Greeks gave us name the Pleiades. But the star cluster was known to other ancient cultures as well. The Bablylonians referred to them as MulMul or “star of stars.” The Aztecs knew them as Tianquiztli. To the Maya, they were Tzab-ek. The Chinese, Persians, Australian Aborigines, Native Americans and Persians all have stories about this prominent cluster near the shoulder of Taurus, the Bull.
Explore the image. Do you notice the color of the stars? The cluster is fairly young and is dominated by hot, blue stars. Astronomers believe the cluster formed about 100 million years ago. And while clusters like this are born out of huge clouds of gas and dust, the misty star cloud around the cluster is just a nebula that the star cluster is passing through. The cloud reflects the blue light of the brightest stars in the Pleiades. Astronomers call this a reflection nebula.
The Pleiades are just 440 light years away from Earth making it one of the closest star clusters to Earth. The core of the cluster is packed in an area about 8 light-years across. A light-year is the distance traveled by light in one year; about 6 trillion miles. The cluster is more spread out, however. In a starship traveling at the speed of light, it would take us 43 years to pass through the entire star cluster. The Pleiades move through space as a group. In a few thousand years they will pass near the feet of Orion as seen from Earth. The stars in the cluster also will drift apart and disperse.