In the Sky This Month

Omega Centauri is the biggest globular star cluster in the galaxy, containing about 10 million stars. From the southern two-thirds of the United States, it is quite low in the south at nightfall. It looks like a faint, fuzzy star.

Ophiuchus, the serpent bearer, climbs across the south at this time of year. Many star clusters are found inside the constellation’s borders. The list includes 10 fairly bright globular clusters, which are tight balls of hundreds of thousands of stars.

The constellation Ophiuchus, the serpent bearer, is low in the sky at nightfall, stretching from due east to due southeast. Its main pattern resembles the outline of a coffee urn. The urn is on its side in early evening but stands upright later in the night.

The Moon completes the first quarter of its month-long loop across the sky at 10:30 p.m. CDT tonight. At this first-quarter phase, the Moon lines up at a right angle to the Earth-Sun line, so sunlight illuminates exactly half of the lunar hemisphere that faces Earth.

The star Regulus lurks to the left of the Moon at nightfall. It is the brightest star of Leo, the lion. The star is much bigger, heavier, hotter, and brighter than the Sun. A “dead” companion star orbits just a few million miles away.

Scorpius skitters across the southern sky. Its head and heart clear the southeastern horizon as darkness falls, and the scorpion remains visible throughout the night. Its brightest star is reddish-orange Antares, in the middle of the scorpion’s body.

Castor and Pollux, the twins of Gemini, are dropping down the western sky on these late spring nights. They line up to the right of the Moon tonight. Brighter Pollux is closer to the Moon, with Castor to its right.

Pisces, the fishes, is low in the east at first light, although you’ll need a starchart to pick it out. Astronomers recently scanned one of its stars for signs of radio signals from any civilization there, but came up empty.

The jewel of the northern crown is high in the east at nightfall and passes overhead a few hours later. Alphecca is the brightest star of Corona Borealis, the northern crown — a semicircle of stars that looks like a tiara.

The crescent Moon is quite low in the sky shortly after sunset. The planet Venus, the Evening Star, is close above it, with the fainter planet Mercury a little higher still. The asteroid Vesta is to the left of Mercury, but you need optical aid to pick it out.