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The Sky This Week, 2020 May 5 - 12

Mother's (Day) Moon
The Moon, 2020 May 5, 02:51 UT.  Color saturation stretched to reveal minerology.
The Moon, 2020 May 5, 02:51 UT, imaged from Alexandria, Virginia.
Image made with a 10.2-cm (4-inch) f/6.5 Explore Scientific AR102 refractor, 1.6X Barlow lens,
and a Canon EOS Rebel SL2 DSLR.
Color saturation has been stretched to reveal minerology.

The Moon wends her way southward along the ecliptic this week, bathing the rising summer constellation with her brilliant glow.  Full Moon occurs on the 7th at 6:45 am Eastern Daylight Time.  May’s Full Moon is popularly known as the Grass Moon, Flower Moon, Milk Moon, Corn Planting Moon, or (in honor of an important day) Mother’s Moon.  Each of these reflects a spring tradition observed by various cultures that have managed to find their way into our sky lore.  If you are up before the Sun on the morning of the 7th, you will find Luna just over two degrees north of the second-magnitude star Zubenelgenubi in the obscure Zodiacal constellation of Libra, the Scales.  Look for the Moon a few degrees south of Jupiter before dawn on the 12th.  The Moon, Jupiter, and Saturn will form an attractive triangle that morning for budding astrophotographers.

Unfortunately the nearly-full Moon washes out the annual Eta Aquariids meteor shower, which peaks in the first half of the week.  This meteor stream is usually quite consistent from year to year, and the meteoroids trace their origins to the venerable Halley’s Comet.  The shower radiant is in the constellation of Aquarius, the Water-bearer, and rises shortly before sunrise in the southeast.  The shower favors observers in the southern hemisphere, but under dark skies observers in the north usually see around 20 to 30 meteors per hour.  This year the bright Moon will severely limit those numbers.

Bright moonlight limits our ability to see all but the brightest stars in the night sky.  For several evenings around the dates of Full Moon it doesn’t really matter if you’re in the city or the country; either way Luna limits the faintness of stars that you can see.  During these brighter times the celestial targets that we can look at are limited.  Even the Moon herself is almost too bright to look at through the telescope!  Fortunately there are a number of interesting targets for the small telescope to keep you out under the vault of the night sky.  These are the nights to hunt down double stars, which are actually quite endemic to the sky.  If you look at the star Zubenelgenubi near the Moon on the evening of the 6th, binoculars will reveal it to be a very wide pair of 3rd-manitude stars.  If you have a small telescope, look for Mizar, the star that forms the bend in the “handle” of the Big Dipper.  If you are blessed with keen eyesight, you may just be able to make out a faint star next to Mizar known as Alcor.  It was said that the ability to see these two with the unaided eye was once used as a test to join the Roman army!  However, if you point a small telescope at Mizar itself, you will see it split into two components.  Now move across the zenith to Leo, the Lion, and look for its brightest star Regulus.  Just north of Regulus is second-magnitude Algieba, which resolves into a close pair of golden stars, one of the prettiest doubles in the sky.  Finally, midway between Denebola, the “tail” of Leo, and the bright star Spica in Virgo you’ll find third-magnitude Gamma Virginis.  Also known as Porrima, this is one of the few double stars whose orbital motion can be seen from year to year.

Over the course of the past few months, dazzling Venus has flown eastward from the stars of the autumnal sky to her current perch high on the ecliptic among the departing stars of winter.  This week she comes to a screeching halt just over a degree west of the star El Nath, the second-brightest star in the constellation of Taurus, the Bull.  Next week she will begin a precipitous plunge toward the Sun, dropping toward the horizon like a stone.  Enjoy the views of her over the next couple of weeks.  By the end of May she will be lost in the glare of the Sun.

Jupiter and Saturn receive a call from the waning gibbous Moon before dawn on the 12th.  The two planets are now about five degrees apart and should be well-placed for viewing in the southeast as morning twilight begins to brighten the sky.  Saturn reaches the first stationary point in this year’s apparition on the 9th, while Jupiter will reach his early next week.  The two planets will gradually assume retrograde motion through the stars of western Capricornus as summer creeps ever closer.

Ruddy Mars is now well to the east of the gas giants, drifting from eastern Capricornus into the stars of Aquarius.  You will find his pink-hued glow low in the southeast in the growing morning twilight.  He is gradually brightening and his telescopic disc is growing as Earth begins to close the gap between us.