In the Sky This Month

Delphinus, the dolphin, glides through the Milky Way on summer evenings. It rises in early evening and arcs high across the south during the night. Look below the Summer Triangle, which is well up in the east and northeast at nightfall.

One centaur is dropping from view as darkness falls while another is climbing into view. Centaurus is low in the south at nightfall, with much of its body below the horizon. The other, Sagittarius, is just rising in the southeast. It climbs into good view a little later.

Vulpecula, the fox, stands quite near the “bill” of Cygnus, the swan. The little constellation is a third of the way up the eastern sky as night falls, near the center of the bright Summer Triangle.

Summer returns to the northern hemisphere early tomorrow. It’s the summer solstice, the point where the Sun stands farthest north for the entire year. The solstice also brings the year’s longest days north of the equator.

The planet Venus is just peeking into view in the dawn sky. Tomorrow, it’s close to the crescent Moon as the sky brightens, quite low in the east-northeast. It’s the brilliant “morning star.” It will climb into better view over the coming weeks.

Perseus is in the northeast at first light. The core of a galaxy in the constellation is churned up by two supermassive black holes at its heart. The galaxy is quite faint, but you can see its position, roughly half way between the stars Epsilon and Xi Persei.

The stars that outline the Summer Triangle stand out this week. There’s no Moon in the evening sky, so the stars don’t have to compete with its glare. The triangle stands low in the east and northeast at nightfall, and wheels high overhead during the night.

Under clear, dark skies, the galaxy M81 is visible through binoculars. Find the Big Dipper, which is high in the north at nightfall, then scan to the lower right of the dipper’s bowl. M81 looks like an oval smudge of light almost as wide as the Moon.

The Moon reaches its greatest distance from Earth for its current orbit this evening. It will be more than 251,400 miles away, which is about 13,000 miles farther than its average distance.

The stars that mark the heads of Hercules and Ophiuchus are close together in the east this evening. Each has an Arabic name that means “the head.” In Hercules it’s Ras Algethi (head of the kneeler); in Ophiuchus, Ras Alhague (head of the serpent charmer).