Akira Fujii

Many casual skywatchers don't realize that simple binoculars can open the door to the exciting hobby of deep-sky observing. Double stars, bright and dark nebulae, distant galaxies, and star clusters are all visible with small binoculars. And among these deep-sky objects, open star clusters are some of the most rewarding to observe. Three are conveniently located high overhead as darkness falls during late February and early March.

You can use our Interactive Sky Chart to help locate them. Start by finding the roughly pentagon-shaped constellation Auriga, with brilliant, yellowish Capella at its northwest corner. Auriga appears near the center of the chart at about 8 p.m. Just off the pentagon's southeastern side you'll see a symbol labeled M37. This is the cluster Messier 37, which is the easiest of the three to spot (and it can even be glimpsed with the unaided eye under a clear, dark sky). Observers with 7x35 binoculars have commented on its beauty. While you may see only a handful of individual stars, the group contains roughly 1,800 suns.

Before moving on to the next cluster, check the field of view of your binoculars, which is usually printed next to the right eyepiece and is given either as an angle or as the width of the field at a distance of 1,000 yards. Small binoculars typically have fields between 5° and 7° wide, which is between 260 and 370 feet at 1,000 yards. If your binoculars fall within this range, then the next star cluster, M36, will lie about half a field of view west-northwest of M37. M36 appears a little fainter and more compact than M37, since it only contains about 60 stars.

The last cluster, M38, lies another half binocular field to the west-northwest of M36. Its appearance is similar M37's, and there are about 160 stars within the group. These three clusters are roughly 4,000 light-years from us, so their light that you see tonight originated around the time the great pyramids were being built in Egypt.

If these clusters whet your appetite for more, just sweep your binocular view southward along the Milky Way toward Orion and Canis Major. Scores of opens clusters await your discovery.


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