For May, the full Flower Moon occurs on May 5th. It is last quarter on May 12th, rising about midnight, when it is passing just south of Saturn. In the dawn sky, the waning crescent passes just north of Jupiter on May 17th, Mercury will lie just south of them in twilight. The new moon is on May 19th. The waxing crescent passes two degrees north of brilliant Venus on May 23rd, and four degrees north of much fainter Mars the following evening. It is first quarter on May 27th.
Mercury passes between us and the Sun on May 1st, and is the dawn sky near Jupiter by month’s end. Venus chases Mars in the west, but will no catch him. She reaches greatest eastern elongation on June 4th, 45 degrees east of the Sun and appears half lit as viewed from earth. Mars lies just above her then, but she will turn around and retrograde westward between us and the Sun in July, while Mars continues moving eastward as it orbits the sun. Mars will be lost in the Sun’s glare by the end of summer, but by then, Venus will pass between us and the Sun and become a morning star for the rest of 2023. Jupiter is just emerging low in the SE dawn sky, while Saturn is at quadrature, 90 degrees west of the Sun in the SE morning sky.
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. For a detailed map of northern hemisphere skies, about April 30th, visit the www.skymaps.com website and download the map for the new month; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. Also available is wonderful video exploring the sky, available from the Hubble Telescope website at: www.hubblesite.org/explore_astronomy/tonights_sky/. Sky and Telescope has highlights at www.skyandtelescope.com/observing/astronomy-podcasts/ for observing the sky each week of the month.
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 NW 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" SE 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.
Because we live farther south than most Americans, we get a fine view of the closest and brightest globular star clusters, Omega Centauri, on May evenings. From a dark sky site, you can spot it with your naked eyes about 12 degrees above the southern horizon when it is at its highest in the south, about 9 P.M. at the end of the month. It is fine in binoculars, and resolves beautifully into about a million sun with larger scopes.
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! Still, it is smaller and farther away than omega, and pales in comparison, but is high enough to be observed for observing it for several hours. Omega is only out for about two hours an evening in the far southern sky.
