In the Sky This Month

The Moon’s prominent companion tonight is the planet Jupiter. It looks like a brilliant star to the lower left of the Moon. Through binoculars, Jupiter’s four big moons look like tiny stars near the giant planet.

The planet Jupiter looks like a brilliant star well to the upper left of the Moon tonight. The brightest stars of Taurus, Aldebaran and Elnath, line up below and above Jupiter, respectively, while the Pleiades star cluster is close below the Moon.

Gaia BH1 is the closest black hole yet discovered, just 1,560 light-years away. It is in Ophiuchus, the serpent bearer, which is high in the south at first light. Its outline looks like a giant coffee urn. BH1 is inside the urn.

The star at the top of Leo’s head has many aliases. Its proper name is Algenubi, from a longer Arabic name that means “the southern star of the lion’s head.” Most astronomers call it Epsilon Leonis. But like most stars, it has several dozen other designations.

The lion springs high across the sky on spring evenings, led by Regulus, one of the brighter stars in the night sky. Denebola, the tail, is no slouch, either. It’s bigger, brighter, and heavier than the Sun. It is a third of the way up the eastern sky at nightfall.

A partial solar eclipse will dim the skies over the northeastern United States early tomorrow. At the peak of the eclipse, the Moon will cover about 90 percent of the solar disk. For the rest of the U.S., the eclipse will be over by the time the Sun rises.

Argo, the ship of Jason and the Argonauts, sails across the south tonight. It originally was a single constellation, but astronomers broke it into four smaller ones: Carina, the keel; Vela, the sail; Puppis, the poop deck; and Pyxis, the compass.

Messier 3 is a globular star cluster – a dense ball a few hundred light-years across. Its stars are among the oldest in the galaxy. The cluster is in Canes Venatici, the hunting dogs, and is low in the east-northeast in early evening. It’s easy to see with binoculars.

Boštes the hunter climbs into view in early evening, marked by the bright yellow-orange star Arcturus, which is low in the east by 9 or 10 p.m. One of the largest “voids” in the universe, an empty region known as the Great Nothing, stretches to the upper left of Arcturus.

Our home galaxy, the Milky Way, belongs to a small cluster of galaxies known as the Local Group. But most galaxies reside in more impressive clusters. The closest of these is the Virgo Cluster, centered in Virgo, which steps up the eastern sky this evening.