For May, the moon passes 2 degrees north of Mars in the western evening sky on May 3rd. It is first quarter moon on May 4th. Setting at midnight, it will not interfere with the peak of the eta Aquarid meteor shower the next morning. These bits of Comet Halley debris will give us a meteor about every five minutes, coming out of the SE sky. The comet itself is on the far edge of its 76 year orbit, and will not be coming back until 2061, but its many trips around the sun have distributed its dust all around its very oval orbit by now. This debris is outbound; the incoming dust arrives as the Orionid meteors in October.
The Full or Flower Moon is on May 12th. The Moon is Last Quarter, rising at midnight, on May 20th. On the 22nd, the waning crescent moon passes three degrees north of Saturn in the dawn. The following dawn it is four degrees north of brilliant Venus. It is new moon on May 26, nut no eclipses until the next eclipse season in September. Low in the NW, the thin waxing crescent moon passes five degrees north of Jupiter on May 28th.
Mercury is low in the dawn as May begins, and passes into its glare by mid month. Venus, by contrast, dominates the dawn, pulling away from the Sun day by day, to reach its greatest western elongation of 46 degrees on May 31. Until then, it is a crescent, getting smaller but thicker daily, but on the edge of its orbit at month’s end, it will appear exactly half lit from earth.
Mars is high overhead in Gemini as May begins, but gets lower each evening. Jupiter is already low in the NW as May begins, and by May’s end, is also disappearing into the glare of the Sun.
But low in the dawn, Saturn makes an interest target for telescopic observers. At month’s start, we can see beneath the ring plane at the dark underside of the rings, but on May 6th, Saturn is at equinox, with its equator and rings facing the sun directly. The rings will very briefly cast only a thin shadow on the disk, and will probably disappear for almost all telescopes on earth. After that, for the next seven years, the rings open more as seen from earth, to be tilted 27 degrees open at its next solstice in 2032.
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 look just east of the bottom of the two stars in the pointers of the Big Dipper, you find a pair of very different deep sky objects in the same field of view with my new See Star S 30.
The bright star is beta Ursa majors, the pointer farther away from Polaris. Below it is the Owl Nebula. With larger scopes, it appears to have two "eyes" around its white dwarf central star. This planetary nebula is the likely fate of our solar system in about six billion years. But at top left is the far more distant galaxy M 108. While they appear in the same binocular field as seen by us, the bluish nebula is only 2,600 light years away, and only created by the collapse of the red giant 8,000 years ago. The galaxy M 108, known as the "Surfboard", is 46 million light years away, and larger than our own Milky Way. It too is a barred spiral galaxy like ours.
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
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. Just SW of Spica is one of most famous, the Sombrero, M-104.
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 10 at the end of the month. Ideally, observe it at the beach, where the Gulf is your southern horizon. 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. It is much more conveniently placed for observing all night, and is a real showpiece in any big scope.
