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The Sky This Week
U.S. Naval Observatory's Weekly Blog
Changing of the Guard
by Geoff Chester, USNO Public Affairs
29 March 2022
The "Leo Triplet" of galaxies, NGC3628 (top), Messier 66 & 65 (bottom, left & right), imaged 2022 March 27 from Mollusk, Virginia
with an Explore Scientific AR102 10.2-cm (4-inch) f/6,5 refractor, Celestron AVX equatorial mount,
and a ZWO Optical ASI183MC CMOS imager. These galaxies are about 35 million light-years away.
The Moon returns to the evening sky by the end of the week. The first of April’s two New Moons occurs on the 1st at 2:24 am Eastern Daylight Time. You should be able to see the slender crescent Moon in the western sky in the deepening twilight on the evening of the 2nd. If you want a true observing challenge, try to spot the hairline lunar crescent just above the western horizon on the 1st. Luna will only be 18 hours past New for observers on the east coast of the U.S., and you might need binoculars to spot her. You will need to have a clear evening and a flat western horizon as the crescent will only be two degrees above the horizon some 20 minutes after sunset. Observers on the west coast will have a somewhat better chance to see this very young crescent since they will have an ocean horizon and the Moon will be slightly higher in the fading twilight. Luna quickly climbs into the evening sky, and you will find her cozying up to the Pleiades star cluster on the evening of the 4th.
You still have a few nights to contribute observations to the
Globe at Night
citizen-science program. As we mentioned last week, the target constellation is Leo, the Lion, which is high in the eastern sky by 10:00 pm local time. Leo’s outline should be easy to find from semi-rural skies, and his brightest stars should be visible from the suburbs in the absence of direct night lighting. I had a chance to see him in all of his regal feline glory this past weekend from Virginia’s Northern Neck, and I submitted an observing report to the
Globe at Night web app
using my smart phone while out with my telescope. The current campaign runs through the 2nd, so you still have a few chances to make your own contribution to science in the crisp of a spring night.
Winter’s bright constellations are still prominent in the western sky as evening twilight fades to night. The distinctive pattern of Orion is well-placed in the southwestern sky at 9:00 pm, and his bright companion stars are still easy to spot. If you have binoculars or a small low-power telescope, sweep the area between Orion and the bright yellow star Capella in Auriga where you will find a number of bright star clusters. Another good hunting ground for these is the area bounded by the stars Betelgeuse in Orion, Sirius in Canis Major, and Procyon in Canis Minor. Here you will find a faint region of the Milky Way and the obscure constellation of Monoceros, the Unicorn.
As Leo moves to the meridian by midnight, the star clusters and nebulae of the winter sky are replaced by fuzzy objects of an entirely different nature. The area bounded by Denebola, the “tail” of Leo, the bright rose-tinted star Arcturus, and the bright blue star Spica is speckled with hundreds of external galaxies that belong to the Virgo Galaxy Cluster. Several dozen of the brighter ones can be seen inn small telescopes, and larger apertures reveal several hundred more. The heart of the cluster is located about 50 million light years away from us, but we still “feel” its influence. Our Milky Way galaxy is a far-flung member of cluster.
Between us and the Virgo cluster is a scattered group of faint stars that can only be easily seen under dark skies. Its brightest stars are only of fourth magnitude in brightness, but up to 60 stars may be glimpsed far from urban areas. The group has been recognized since the time of Ptolemy as the constellation Coma Berenices, the Hair of Queen Berenice, which she offered as a sacrifice for the safe return of her husband from battle in 245 BCE. About 50 of the visible stars are part of a star cluster located 290 light-years away.
The bright planets are still clustered in the pre-dawn sky, visible in the southeast as morning twilight begins to brighten the sky. Venus leads the parade, beaming brightly through the gradual increase in sky brightness. Trailing a few degrees to the right of Venus is ruddy Mars, and in between the two is the yellow glow of Saturn. Watch mars close in on Saturn by the end of the week. On the morning of the 5th they will be less than half a degree apart.
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