June Starwatch

by Deane Morrison

The sun holds sway during this month of short nights, but when its glow finally disappears, the summer constellations make it worth the wait. Unlike their winter counterparts, they spread bright stars rather evenly across the night sky.

In the west, Leo heads toward the sunset, but this time with two companions. Just east of Regulus, its brightest star, Saturn glows a soft gold. Swooping in from the west, ruddy Mars almost catches up to Regulus by the end of the month. Through binoculars or even with the unaided eye, you may be able to pick out the varied hues of these three objects.

Moving east, kite-shaped Bootes, the herdsman, floats high, anchored by brilliant Arcturus. Below Bootes, the bright star Spica marks the large but otherwise dim constellation Virgo. But Virgo, especially its northern part, contains one of the most astounding structures known to astronomy: the Virgo Cluster, a gigantic, unruly spread of more than 2,000 galaxies. It is the closest cluster of galaxies to a smaller array known as the Local Group, to which our Milky Way belongs.

Looking still further east, the Corona Borealis, or Northern Crown, hangs next to Bootes. Then come Hercules and the Summer Triangle of Vega (next to Hercules) and Deneb toward the north and Altair in the south.

Near the southeastern horizon, the S-shaped form of Scorpius is coming up. Its red heart, Antares, is one of the largest stars known, with a diameter several hundred times that of our sun. Antares is getting close to the end of its life as what astronomers call a red supergiant, and someday will explode in a supernova 10 billion times as bright as the sun. If that happens in our lifetime, we'll see it light up the night with twice the radiance of the full moon. When the glow fades, however, we'll have lost a real treasure.

East of Scorpius come the Teapot of Sagittarius and the summer's planetary star, Jupiter. The giant planet rises earlier each evening as Earth catches up to it in the orbital race. Although low in the sky, it dominates the night with its luminosity. Above it hangs the Teaspoon of stars, which not only sounds as though it belongs near the Teapot but, like its larger companion, actually resembles its namesake object.

A crescent moon will sweep by the Mars-Regulus-Saturn trio between the 7th and the 9th. The full moon, called the strawberry moon or rose moon, arrives on the 18th.

The summer solstice occurs at 6:59 p.m. CDT on the 20th. At that moment, the sun will be directly over the Tropic of Cancer and won't set till 9:03 p.m. in the Twin Cities area, later for points north. The word "solstice" means "sun standing still," and so it seems to do during June. The sun moves rapidly north in the spring, but slows down and spends about a month on either side of the summer solstice lingering high in the northern sky.