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Target open clusters

The winter sky is teeming with breathtaking targets. Where, oh where, to begin? Orion? Canis Major? Gemini?

Those will all come in due time, but this month I’d like to focus on two of the most dazzling open star clusters visible through binoculars. And they lie almost next to each other in Taurus the Bull. I am referring, of course, to the Hyades and the Pleiades. Both can be readily seen with the unaided eye. But through binoculars, each explodes with stardust.

Let’s start with the Hyades. You probably know them as the Bull’s V-shaped head, with brilliant Aldebaran marking his angry red eye. Nearly 400 stars are held within the group’s 5.5° span. A third of these shine brighter than 9th magnitude, the limit for many binoculars under suburban conditions. Most can squeeze them all into a single field of view.

The Hyades collectively floats 151 light-years away, making it the closest open star cluster to our solar system. Aldebaran, however, is closer still, only about 60 light-years away. So, while it adds color and pizzazz, its location is purely coincidental. That means the cluster’s brightest star, at magnitude 3.4, is actually yellowish Theta2 (θ2) Tauri. Theta2 joins with magnitude 3.8 Theta1 (θ1) Tauri to form a wide naked-eye binary star. Both are southwest of Aldebaran.

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