This week Hal tells us about M 67, the oldest open star cluster in the entire Messier catalog.
We’ve talked before about objects in the southern Colorado and northern New Mexico sky that appear on 18th-century astronomer Charles Messier’s list of things not to look at. Messier was a comet hunter, and he kept getting confused by objects in the sky that turned out not to be comets.
Today, let’s talk about the 67th item he cataloged, a cluster of stars in the constellation Cancer, high in our evening sky right now. M 67, as it is called, through binoculars or a small telescope resolves into what astronomers call an open cluster – a group of stars that likely formed from the same vast cloud of gas and dust many years before. And while there are many open clusters in the sky, M67 is a special case, and is worth taking a look at.
Roughly 2600 light years away, and now expanded to about 12 ly in diameter, M67 might look like a regular open cluster. It contains about 500 stars, and takes up roughly the same area in the sky as the full moon, and it is lovely to look at. But what makes it special is its age.
You see, M 67 is the oldest open star cluster in the entire Messier catalog, at nearly 5 billion years of age. This isn’t super old, astronomically speaking. But most clusters of stars like M 67 have spread out into space and dispersed, but the stars in M 67 seems intent on sticking together. As a result, it’s had time to work its way 1500 light years outside the plane of the Milky Way galaxy. You might say M 67 has moved to the suburbs. So be sure and come to a star party so we can show you a beautiful cluster of stars that seems intent on moving out of the neighborhood.
If you’d like to take a closer look at M67, or any of the other wonderful and amazing things in the sky, please visit KRCC.org or CSASTRO.org for a link to information on our monthly meetings and our free public star parties!
This is Hal Bidlack for the Colorado Springs Astronomical Society, telling you to keep looking up, Southern Colorado!