For May 2020, the first quarter moon occurs on April 30, and the Full Moon, the Rose Moon, occurs on May 8. The waning gibbous moon passes two degrees south of bright Jupiter on May 12, and then three degrees south of fainter Saturn a few hours later. The last quarter moon passes three degrees south of Mars in the morning sky on May 14. New moon is on May 22. The evening of May 23 will give us a fine conjunction in the west about 7:30 p.m., with the thin crescent moon to the lower left of brighter Venus, and fainter Mercury will be above them. You may need binoculars and a very clear western horizon to spot this trio. By the following evening, the much easier crescent moon will be above both, with faint Mercury lying midway between the Moon and bright Venus, to the lower right. Great photo ops! The first quarter moon occurs on May 29.
While the naked eye — dark adapted by several minutes away from any bright lights — is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. Visit www.skymaps.com for a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map.
Mercury and Venus are both visible in the west this month, and perform an interesting planetary dance. As May begins, only Venus is visible, well up in the west, and 24% illuminated crescent some 33” of arc wide. But as Venus drops lower each evening, heading to inferior conjunction in June, Mercury rises from the far side of the Sun to produce a close conjunction on May 21; now Venus is much closer, some 53” across, but only 6% sunlit, a very thin crescent obvious in binoculars. Fainter Mercury is only 7” across, but a gibbous 70% still in sunlight. Can you see both disks at the same time in low power telescopes? The following evening, the thin crescent moon joins the club, as described above. By month’s end, Venus is very close to the Sun and only 1% sunlit, but Mercury is much easier to spot at greatest eastern elongation, half lit and 23 degrees east of the setting sun.
We are overtaking Mars, to pass closest to it this October. It moves eastward from Capricornus into Aquarius in the dawn sky, and brightens from first to zero magnitude by month’s end. Both Jupiter and Saturn are also in the dawn sky, with brighter Jupiter about five degrees west of fainter Saturn between the teapot of Sagittarius and the triangle of Capricornus.
The winter constellations will soon be swallowed up in the Sun’s glare, but Orion is still visible, with its famed Orion Nebula, M-42, seen below the three stars marking his famed belt. Dominating the southwest is the Dog Star, Sirius, brightest star of the night sky. When Sirius vanishes into the Sun’s glare in two months, this sets the period as “Dog Days”.
The brightest star in the northwest is Capella, distinctively yellow in color. It is a giant star, almost exactly the same temperature as our Sun, but about 100X more luminous. Just south of it are the stellar twins, the Gemini, with Castor closer to Capella, and Pollux closer to the Little Dog Star, Procyon.
Overhead, the Big Dipper rides high. Good scouts know to take its leading pointers north to Polaris, the famed Pole Star. For us, it sits 30 degrees (our latitude) high in the north, while the rotating earth beneath makes all the other celestial bodies spin around it from east to west.
If you drop south from the bowl of the Big Dipper, Leo the Lion rides high. Note the Egyptian Sphinx is based on the shape of this Lion in the sky. The “regal” star Regulus marks the heart of the celestial lion.
Taking the arc in the Dipper’s handle, we “arc” southeast to bright orange Arcturus, the brightest star of spring. Cooler than our yellow Sun, and much poorer in heavy elements, some believe its strange motion reveals it to be an invading star from another smaller galaxy, now colliding with the Milky Way in Sagittarius in the summer sky. Moving almost perpendicular to the plane of our Milky Way, Arcturus was the first star in the sky where its proper motion across the historic sky was noted, by Edmund Halley. Just east of Arcturus is Corona Borealis, the “northern crown”, a shapely Coronet that Miss America would gladly don, and one of few constellations that look like their name. The bright star in the crown’s center is Gemma, the Gem Star.
Spike south to Spica, the hot blue star in Virgo, then curve to Corvus the Crow, a four-sided grouping. The arms of Virgo harbor the Virgo Supercluster of Galaxies, with thousands of “island universes” in the Spring sky. We are looking away from the place of thickly populated Milky Way, now on the southern horizon, toward the depths of intergalactic space, where even amateur telescopes can spot quasars billions of light years distant.
To the northeast Hercules rises, with his body looking like a butterfly. It contains one of the sky’s showpieces, M-13, the globular cluster faintly visible with the naked eye. Find it with binoculars midway on the top left wing of the cosmic butterfly, then take a look with a larger telescope and you will find it resolved into thousands of stars.
For more information on the Escambia Amateur Astronomers, visit the Escambia Amateur Astronomers Facebook group or visit www.eaaa.net or call sponsor, Lauren Rogers at Pensacola State at (850) 484-1155 or lrogers@pensacolastate.edu. To be added to the astro alerts for gazes, ISS passes, club photos, etc., contact Dr. Wooten at wwooten@pensacolastate.edu. We also will send you a free copy of “Star Shooting”, our photo gallery of 1,500 of the best local astrophotos over the last 30 years of recording the sky. Be sure to include your P.O. mailing address in the email.