Four star clusters hang out above the “head” of Canis Major, the big dog. As night falls, they’re to the left or upper left of Sirius, the brightest star in the night sky. They wheel above the Dog Star as the night goes on.

The clusters are known as NGC 2323, -35, -43, and -53. Each one is a family of dozens to hundreds of stars. And all of them are fairly young — a hundred million years old or so. That may not sound young until you compare it to the age of the Sun — four and a half billion years.

In fact, that entire region of the sky is awash in young stars — and in stars that are still being born. Big clouds of gas and dust in the region are collapsing. Some of them are compressed by exploding stars, others by radiation and winds from hot young stars. As the clouds collapse, they break into smaller and smaller fragments. Those fragments, in turn, collapse to make stars.

NGC 2343 is the brightest of the four clusters near the big dog’s head. Under dark skies, good binoculars reveal two or three dozen individual stars. The cluster is more than 3,000 light-years away. It’s on the edge of one of the star-forming clouds, and may be the result of an earlier wave of starbirth from the same complex.

NGC 2335 is also on the edge of that complex, and it’s also fairly bright. Even so, you need dark skies and binoculars or a telescope to see this family of young stars above the head of the big dog.

Script by Damond Benningfield

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