Space and Astronomy Megathread (MERGED) - Part 1

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Comet Tsuchinshan-ATLAS Flys Away
Image Credit & Copyright: Xingyang Cai
 
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Cometary Globules
Image Credit & Copyright: Mark Hanson & Martin Pugh, Observatorio El Sauce
 
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Globular Star Cluster NGC 6752
Image Credit & Copyright: Massimo Di Fusco, Aygen Erkaslan
 
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Phantoms in Cassiopeia
Image Credit & Copyright: Christophe Vergnes, Hervé Laur
 
An old trick to identifying stars near the Big Dipper.

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The two stars in the “bowl” of the Big Dipper (opposite the “handle”) are appropriately called “the pointers.” Use them as a directional guide to Polaris — which is about the width of the Big Dipper away from "the pointers." Polaris isn’t very bright. But if you can make out the Little Dipper, Polaris is the last star in its “handle.”

In the other direction, “the pointers” of the Big Dipper direct you to Regulus. Though a bit farther away, Regulus is easier to spot because it’s quite bright.

Now use the bent handle of the Big Dipper to guide you to Arcturus. Arcturus is actually one of the brightest stars in the northern sky. And from Arcturus, continue on to Spica (also reasonably bright). Memory device: from the “arcing” handle of the Big Dipper… “arc on over to Arcturus and then speed on to Spica.”

Throughout the year, the Big Dipper rotates in the sky. But no matter its orientation, “the pointers” always point to Polaris. (Of course, one needs to be in the Northern Hemisphere. :word:) Those other stars, however, may not always be visible — due to being below the horizon.

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An interesting graphic showing the 10 closest stars to Earth (in addition to the Sun).

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But of these, only two (or three) are visible to the naked eye. One is Sirius, the brightest star in the sky. Alpha Centauri A and B (a binary seen as a “single” star) is/are also quite bright. But you have to be in southern latitudes to observe it. The rest are all red dwarfs and invisible to the unaided eye. If you knew where to look, you could see Lalande 21185 with a pair of binoculars. But something like Proxima Centauri or Wolf 359 require a good-sized telescope.

Also close by (though not included in the graphic) are the “brown dwarf” stars Luhman 16 and WISE 0855-0714. But as the name implies, brown dwarfs are even dimmer than red dwarfs. Both were discovered only in this century.
 

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