In May the evening sky ushers out the bright winter stars and nudges Leo, the lion — the most prominent spring constellation — toward the western exit. Nightfall comes late, but when it does it reveals the second and third brightest stars in our night sky.

High in the southeast blazes Arcturus, the brightest star in the northern hemisphere of the sky. Only marginally dimmer, brilliant Vega shines lower in the northeast to east. Both stars climb throughout the month, along with their constellations. At 37 light-years distant, Arcturus anchors kite-shaped Bootes, the herdsman, while Vega, at 25 light-years, dominates the small constellation Lyra, the lyre.

In the second half of May, Spica — the only bright star in Virgo, the maiden — will be almost due south at nightfall, below and slightly west of Arcturus. Spica contains two stars, both larger than the sun, separated by just 11 million miles, or 12% of Earth’s distance from the sun. These stars orbit their common center of mass in just four days. It’s thought that their intense mutual gravity deforms both stars into an egg-like shape.

The moon begins the month in the morning sky. Just before dawn on May 3, it appears close above the eastern horizon, to the right of Saturn. After beginning a new cycle on May 7, it visits the Gemini twin stars on May 12; Regulus, in Leo, on May 15; and Spica on May 19. The night of May 22 to May 23, May’s full moon traces a low arc across the sky.

The waning moon appears in the middle of the Teapot of Sagittarius in the predawn hours of May 26. On May 31 it shines below Saturn, which is rapidly moving up and westward through the morning sky. Far to the lower left of the ringed planet, a barely visible Mars is slowly climbing as Earth gains on it in the orbital race.

Minnesota Starwatch is a service of the Minnesota Institute for Astrophysics, located in the Tate Laboratory of Physics and Astronomy in Minneapolis.