Val Germann belongs to the Central Missouri Astronomical Association and has been a member since 1978. He is at MU's Laws Observatory most Wednesdays, showing the sky. He taught astronomy for many years for Columbia College but is now retired. Check Related Media for maps of the constellations Val describes.
Early summer for 2012 offers some very pleasing sky viewing with Saturn and Mars high in the southwest and the moon making some striking combinations with them in both June and July. In spite of the heat this spring the evening skies have been quite clear much of the time. Don’t miss these warm-weather opportunities for great naked-eye views of the moon, planets and constellations.
Though you can see the sky from almost anywhere, it is a great help to have a good view down to the horizon, in all directions, and to be away from city lights if possible. One place in town with great horizons is at Laws Observatory, atop the MU Physics Building, open every Wednesday evening through most of the summer from 8 to 10 p.m. Laser-guided sky tours are done most Wednesdays, and telescopes are also available for the moon and planets. It’s all free and open to the public.
The place to start this summer is high in the southwest where two bright stars dominate the sky. The upper “star” is actually a planet, Saturn, and it will slowly drift to the left, to the east, and away from the lower star, Spica, in the constellation Virgo. In the last week of both June and July, the waxing crescent moon will pass by these two bright sky objects, making for great viewing. The first computer image in Related Media shows the grouping for July 25, a Wednesday.
Notice Mars, which will appear slightly reddish, to the right of Saturn. Mars, too, will be moving east this summer, traveling fast enough to pass Saturn by the beginning of August. The word “planet” means “wanderer” and during this summer of 2012 sky viewers will get a dramatic illustration of that.
Next, turn to the north for great views of the Big and Little Dippers, including the North Star, Polaris and one of the largest of all the constellations, Draco the Dragon.
The Big Dipper, Ursa Major or Great Bear, is halfway up the northwestern sky in early summer as it gets dark. Note the stars at the front of the bowl of this dipper, the “pointers” as they are called, which lead straight to the North Star. This most important star is not super bright, but it is the only star in the sky that appears to stand still all night, as all the other stars seem to rotate around it. This effect is caused by the rotation of the Earth on its axis, the northern end of which points very nearly to Polaris.
Polaris is also at the end of the handle of The Little Dipper, which is standing straight up above the pole this time of year. Note that the Little Dipper is almost like the hand of a 24-hour clock, marking the hours as the night moves along.
Also in the north in early summer is the ancient constellation Draco, a giant dragon, wrapping around the Little Dipper and with its head very high in the sky, almost straight up, at the zenith. This constellation goes back to the Egyptians and Sumerians, thousands of years ago. The brightest star in this constellation, straight above the Little Dipper in summer, was the North Star when the Egyptian pyramids were built, 3,500 years ago. Its name is Thuban, which means “navel” or “axle,” because it was the axle of the sky long ago.
Next we move to the east, along the tree line, where the Great Summer Triangle is making its appearance in midevening. Three constellations make up the triangle, Cygnus the swan, Lyra the harp and Aquila the eagle. Each constellation has a very bright star. Cygnus has Deneb, Lyra has Vega and Aquila features Altair. All three of these stars stand out well without any optical aid and create a giant triangle that’s visible all summer long and even into the fall.
Inside the Summer Triangle is one of the most interesting asterisms, or grouping of stars, in the entire sky. Right in the middle of the triangle is the tiny constellation of Sagitta, which looks like its name: the arrow. If you have a binocular handy, take a look just above Sagitta’s arrow for the Coat Hanger star cluster, which looks exactly like its name, too! It’s one of the most striking features of the summer sky.
We have one more stop to make, straight overhead, for the brilliant star Arcturus in the constellation Bootes, the herdsman. The name “Arcturus” means “bear herder” and Arcturus seems to be herding the Great Bear, the Big Dipper, around the pole, all night long and every night. Arcturus is one of the very brightest stars in the sky and also one of the nearest of all the bright stars, only about 40 light-years away. However, “not very far” is a relative thing among the stars because one light-year is equal to six trillion miles, the distance light travels in 365 days. So, Arcturus is 240 trillion miles distant!
This completes our tour of the most interesting features of the summer sky this year. Try to get out and take a look at some of them, even in your backyard, no matter how situated it is. My backyard is in town and has trees in it but there is still enough sky showing for me to look at something almost every clear night. So, once again, don’t miss the summer sky because it soon enough will change into fall, as the Earth revolves around the Sun, bringing new stars into view.
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