Northern Sky - June 9-22

Northern Sky  -  by Deane Morrison  June 9-22 2018

During the two weeks between June 9 and 22 the moon switches from the morning to the evening sky. It starts out as a waning crescent that drops diagonally toward the sun from morning to morning. On the 13th we get a new moon, at which point the moon crosses to the evening sky and begins waxing.
 
In the western evening sky, Venus continues to outshine everything else. Starting on the 9th, the Gemini twins, which have been dropping toward Venus, start to pass the planet on the right, or, its northern side. The Gemini twin stars are Castor and Pollux, Pollux being the one closer to Venus. On their way toward the horizon, the twins pass the young moon on its way up.  
 
We can see this after nightfall on Friday, the 15th. We’ll have a young crescent moon below Venus and the Gemini twins off to the side. When the sky has darkened on the 16th, grab your binoculars and look for the lovely but subtle Beehive star cluster midway between Venus and the moon. You’ll see two stars bracketing the Beehive to the upper left; these are the Aselli, or asses. In Latin the Beehive is called Praesepe, the manger, and the Aselli are two donkeys feeding at it. On the 19th, the Beehive will appear immediately southeast of Venus, that is, just to its lower left, but by then we’ll have a nearly first-quarter moon that might wash out the stars a bit.
 
Jupiter is up in the south after nightfall. To the west of Jupiter is the bright star Spica, in Virgo. Actually, it’s the only bright star in Virgo. Above these two objects is Arcturus, in Bootes, the herdsman, a kite-shaped constellation. Just east of the kite is Corona Borealis, the northern crown, which looks like a tiara hanging in the sky. Its brightest star is Alphecca, or Gemma, the jewel in the crown. Alphecca is a double star, a pair of stars, one significantly fainter than the other. It’s an example of what’s known as an eclipsing binary. Every 17.4 days, the fainter star passes in front of the brighter star as seen from Earth and causes a slight dip in Alphecca’s brightness. The most famous eclipsing binary is Algol, in the winter constellation Perseus. The variations in its brightness are easily seen. To the ancients it looked like a winking eye in the sky.
 
If you’re up late, camping or just outside with a southern exposure, you can watch the summer stars follow Jupiter into the sky from the southeast. First Scorpius and its gigantic red heart, Antares. Then the Teapot of Sagittarius, with Saturn shining above the lid of the Teapot, and finally Mars, which is brightening by the day. Everything rises earlier every night, but practically speaking, you won’t see Mars till after midnight.
 
The summer solstice happens at 5:07 a.m.—almost exactly sunrise in Grand Marais—on Thursday, the 21st. At that moment the sun reaches a point over the Tropic of Cancer and Earth will be lighted from the Antarctic Circle up to the North Pole and over to the Arctic Circle on the night side of the planet. You may have noticed that the sun is about as high as it gets for about a month before and after the summer solstice. And about as low as it gets for two months centered on the winter solstice. That’s because, of course, the sun moves northward and southward most slowly around the solstices, when it changes direction and appears to stop for a while. In fact, the word solstice is derived from the Latin for “sun standing still.”

Deane Morrison is a science writer at the University of Minnesota.
She authors the Minnesota Starwatch column, and in this feature, she shares what there is to see in the night sky in our region.

"Minnesota Starwatch" can be found on the University of Minnesota website at 
astro.umn.edu.