The Sky This Week
U.S. Naval Observatory's Weekly Blog

Sweeping Through the Winter Milky Way

by Geoff Chester, USNO Public Affairs
25 January 2022

Messier 35 and NGC 2158, imaged 2022 February 22 from Alexandria, Virginia
with an Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor and a Canon EOS Rebel SL2 DSLR camera.

The Moon spends the week waning in the morning sky, passing through the stars of late spring and early summer as she dwindles through her crescent phases.  New Moon occurs on February 1st at 12:46 am Eastern Standard Time.  Look for the Moon just north of the star Dschubba in the “head” of Scorpius before dawn on the 27th.  Luna’s slender crescent will be just three degrees southwest of ruddy Mars in the brightening twilight of the morning of the 29th.

The January campaign for the Globe at Night citizen-science program runs for the duration of the week, and hardy stargazers can test their winter endurance by looking at the stars of Orion.  This is probably the easiest of the campaign’s constellations to look at, since the Hunter’s distinctive shape is visible from every inhabited part of the globe and can be seen even from the heart of major metropolitan areas.  The idea behind the program is quite simple; find Orion in the sky, then compare the number of stars that you can see with charts on the project’s web page.  The Globe at Night project is an internationally recognized program that grew out of the 2009 observance of the International Year of Astronomy.  From these humble beginnings it has grown a world-wide audience of observers, collecting over 25,000 observations during 2021.  The data collected from these monthly campaigns helps astronomers and climate scientists assess the amount of artificial light that’s being directed up into the night sky and helps promote awareness of light pollution and its implications for the environment.   The more people we can sensitize to the issue, the more likely we are to find a solution.

We often talk about the brilliance of the summertime Milky Way, but the faint band of the Galaxy’s glow is also a fixture of the winter sky.  In the summer months we are looking across vast star clouds toward the Galaxy’s center, but during winter we are looking through less dense star clouds toward the Galaxy’s edge.  Our solar system is located much closer to the edge than the center, so the Milky Way’s density is much less in the winter sky.  Nonetheless, under crisp winter skies at dark locations the winter Milky Ways is still impressive.  This is one of my favorite parts of the sky to explore with binoculars or small telescopes.  Scan the sky between Cassiopeia in the northwest to the bright star Sirius in the southeast and you will notice dozens of knots of light, most of which are star clusters.  The Pleiades in Taurus is one of the closest of these clusters, providing pleasing views for the unaided eye and a treat for binocular observers.  High overhead in the constellation of Auriga, the Charioteer, binoculars will reveal several star clusters between the bright stars Capella and El Nath, the latter “shared” with Taurus.  These clusters are best viewed in relatively small, low-magnification telescopes that allow you to “sweep” through the Milky Way’s stars.  One of my favorite clusters is located among the stars that mark the “foot” of Castor, one of the Gemini twins.  Messier 35 is easily seen in binoculars as a misty patch of light that resolves into hundreds of stars in a small telescope.  That telescope will also reveal a faint smudge of light just west of the cluster.  A larger telescope will resolve this glow into another, more remote cluster, NGC 2158.  Dozens of these cosmic “jewel boxes” may be found as you sweep the sky just east of Orion through the faint stars of the constellation of Monoceros, the Unicorn down to the sky’s brightest star, Sirius. 

You can still catch Jupiter in the evening twilight sky, but each passing night brings him inexorably closer to the Sun.  By the end of evening twilight he hangs low in the southwestern sky, and by 7:30 pm he’s setting.  Once he’s gone there are no bright planets to be seen until just before sunrise.  

Mars rises at around 5:00 am local time, and he should be visible low in the southeast an hour later.  He receives a visit from the waning crescent Moon on the morning of the 29th.  

Bright Venus should also be visible in the brightening glow of morning twilight.  You will find her to the east of Mars and the crescent Moon on the 29th.  
 
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