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The Sky This Week, 2021 March 30 - April 6

Lions and galaxies and bears, oh my!
Messier 81 (bottom) and 82, galaxies in Ursa Major, imaged 2021 March 7 from Turner Mountain, Virginia
Messier 81 (bottom) and 82, galaxies in Ursa Major, imaged 2021 March 7 from Turner Mountain, Virginia
with a 10.2-cm (4-inch) f/6.5 Explore Scientific AR102 refractor and a Canon EOS Rebel T2i DSLR

The Moon wanes as she wends her way along the southern reaches of the ecliptic this week.  Last Quarter falls on April 4th at 6:02 am Eastern Daylight Time.  You will find Luna carousing with the rising summer constellations of Scorpius and Sagittarius in the pre-dawn sky.  On the morning of the 6th look for pale yellow Saturn just over four degrees north of the Moon.  On the following morning Luna’s slimming crescent will pass a similar distance south of bright Jupiter.

I’m sure that you have all heard the expression, “March comes in like a lion and goes out like a lamb”.  Indeed, early March is when the constellation of Leo, the Lion becomes prominent in our sky, and by the month’s end the constellation of Aires, the Ram disappears into evening twilight.  Leo figures prominently in our upcoming evening skies as it is the focus on the April campaign for the Globe at Night citizen-science observing project, which runs from the 3rd to the 12th.  Leo’s brightest star, Regulus, is well up in the southeastern sky by 9:00 pm local time, and traditionally marks the site of the Lion’s heart.  From a suburban location you can see a semi-circular asterism above Regulus that resembles a backwards question mark that is popularly known as “The Sickle”.  This grouping forms the Lion’s head.  Some 15 degrees east of Regulus is a right triangle of stars that denote the Lion’s hindquarters.  To participate in the Globe at Night project, simply go outside, let your eyes adapt to the dark for 15 to 20 minutes, then compare the number of stars that you see to the charts on the Globe at Night web app.  Your observation will benefit scientists researching the effects of nighttime outdoor lighting and its effects on the environment.

Leo represents the Nemean Lion, slain by Heracles (the Roman Hercules) as the first of his Twelve Labors.  It holds a number of treats for owners of small and modest-aperture telescopes.  One of my favorite targets is the yellow-hued star Algieba, which lies about 8 degrees north of Regulus.  Through binoculars the golden tint of the star becomes readily apparent, and pointing a small telescope towards it reveals that Algieba is a beautiful close binary star system.  In my 4-inch refractor the stars glow with a deep yellow cast like a distant pair of cat’s eyes.  Under darker rural skies larger telescopes reveal faint smudges of light interspersed among Leo’s stars.  These fuzzy wisps are actually distant galaxies, far removed from the constellation’s stars.  While Regulus shines from 77 light-years away, the constellation’s brighter galaxies shine across a gulf of 20 to 40 million light-years of space!

Leo begins to cross the meridian at around 11:00 pm local time.  If you pivot 180 degrees and look toward the north you will encounter the seven-star asterism known as the Big Dipper.  These are the most prominent stars of the constellation of Ursa Major, the Greater Bear, which occupies much of the northern part of the sky at this time of year.  The five middle stars of the Dipper share a common proper motion through space, and thus seem to be part of a very loose galactic cluster that is currently about 80 light-years from us.  Thirteen stars have been positively identified in the Ursa Major Moving Group, and there may be as many as two dozen more that may be members scattered across the sky.  Like Leo, the stars of Ursa Major lie in front of many external galaxies, making this a prime hunting ground for amateur astronomers with big telescopes.

Lonely Mars spends the week drifting eastward between the stars that form the tips of the horns of Taurus, the Bull.  Over the next several weeks the red planet will form a constantly-shifting triangle with two other red stars, Aldebaran and Betelgeuse.  Look for them in the west as evening twilight fades.

Jupiter and Saturn are still best seen in the gathering morning twilight, low in the southeastern sky.  Jupiter is by far the brighter of the pair and follows Saturn’s rise by about half an hour.  You will have some nice photo opportunities to snap each one with the waning Moon as the week ends.