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Winter Milky Way

January 27, 2016

The frosty outline of our own home galaxy arcs high overhead on these winter evenings. It stretches across or near some of the brightest stars in the night sky — from Sirius, the brightest of them all, low in the southeast; up past bright orange Betelgeuse above it; by yellow-orange Capella high overhead; and down to Deneb, the tail of the swan, low in the west.

That feeble band of light — the Milky Way — represents the combined glow of millions of stars in the disk of the Milky Way galaxy. Yet it’s especially faint at this time of year because we’re looking away from the galaxy’s busy heart and toward its thinly populated hinterlands.

Even so, with even a modest pair of binoculars, you can see some impressive sights within that faint glow.

Many of those sights are star clusters. Each of these groups of scores or hundreds of stars formed from a single giant cloud of gas and dust. The stars remain gravitationally bound to each other, so they travel through the galaxy as a group.

The brightest of them all is within the Orion Nebula, a giant cloud of gas and dust that looks like a fuzzy star below Orion’s three-star Belt. It’s given birth to perhaps a couple of thousand stars in the last few million years. Most of them remain bound together, forming a cluster — one of the youngest and largest in the entire galaxy.

A similar combination of nebula and star cluster sits over in the northwest, and we’ll have more about that tomorrow.

Script by Damond Benningfield, Copyright 2015

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