May will be an exciting month in the sky. As May begins, brilliant Venus and bright Saturn will be close together low in the eastern predawn sky with Mercury near the eastern horizon and probably hard to spot without binoculars. As the month progresses, Mercury will drop quickly toward the Sun, while Venus and Saturn separate as Saturn climbs much faster than Venus into the morning sky. If you are an early riser, it should be interesting to follow these planetary movements. Since Saturn will be in a dim part of the sky, it should be easy to find even when it is far from Venus.

In the evening sky, very bright Jupiter will be dropping into the twilight glow and will be hard to spot by the end of the month. Meanwhile, Mars will be high in the west-southwestern sky. Its eastward motion has taken it away from the bright twin stars of Gemini (the Twins), and it will be moving through the dim constellation Cancer (the Crab). This movement will take it very close past the Beehive open star cluster on about May 4, and it will be close to the cluster for a couple of days before and after. If you ever wanted to see this iconic star cluster that some say looks like bees around a hive, this is an excellent opportunity to find it. Binoculars or a very dark sky will be needed to see the cluster, but with Mars nearby it should be easy.

Although Cancer is the dimmest constellation of the zodiac, it has a long history. It is thought to have been given its name because about 2,500 years ago, the summer solstice occurred when the Sun was in this part of the sky. The motion of the Sun northward and then turning and moving southward may have reminded the ancient skywatchers of the sideways motion of a crab. In Greek-Roman mythology, Cancer represents the crab that was sent to distract Hercules during his battle with the monster Hydra. Hercules crushed the crab, and because it failed, it was given only dim stars when it was placed in the sky.

Another story related to Cancer concerns what currently is called the Beehive star cluster but in ancient times was called the Praesepe or manger. As the story goes, the Greek gods Dionysus and Silenus were riding two donkeys into the battle with the Titans. The loud braying of the donkeys frightened the Titans and allowed the gods of Olympus to win the war. The donkeys then fed at a manger. The manger, along with the donkeys, were placed into the sky.

On May 16, we commemorate Dr. Nancy Grace Roman, NASA’s first Chief Astronomer, who was born in 1925. She created NASA’s space astronomy program, championed larger space telescopes, and helped develop the Hubble Space Telescope.

Observing Highlights

-May 2: The Moon will be close to Pollux, the slightly brighter of the twin stars of Gemini (the Twins). Castor, the other twin star, will be to their right, and Mars will be farther to their upper left.

-May 3: Observe Astronomy Day with the Black Hawk Astronomy Club and Grout Museum at the Imaginarium, 7-9:30. The Moon will be close above Mars and the Beehive open star cluster in Cancer (the Crab), but the bright Moon may make it hard to see the cluster. Mars will be very close to the Beehive on May 4 and 5, and it will be within a binocular field of view of the cluster from about April 21 to May 17.

-May 6: Before dawn, brilliant Venus and dimmer Saturn will be side by side, with Venus on the left. The Moon will be close above Regulus, the brightest star in Leo (the Lion), at nightfall.

-May 9: The Moon will be close above Spica, the brightest star in the constellation Virgo (the Maiden).

-May 13: The bright Moon will rise very close to Antares, the brightest star in the constellation Scorpius (the Scorpion).

-May 23: Before dawn, the Moon will be to the upper right of brilliant Venus and farther to the lower left of Saturn.

-May 28: The Moon will have returned to the evening sky and will be above Jupiter very low in the west-northwestern sky.

-May 31: Star Party sponsored by Grout Museum and Black Hawk Astronomy Club, Prairie Grove Park, Waterloo, 9-10:30 p.m.