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Try to spot the constellation Ursa Major, aka the Great Bear, this month. The constellation is home to the well-known group of stars known as the Big Dipper. Courtesy

June 20 brings us the summer solstice, so warmer weather has hopefully arrived in Wyoming.

This month, if you go out after it gets dark, you will see some wonderful stars and constellations in every direction. If you face north, you will see a “w” above the northern horizon, and these five stars are the constellation Cassiopeia. The Little Dipper, also known as Ursa Minor, is halfway above the northern horizon. Almost overhead you can see the Big Dipper, the well-known stars making up part of Ursa Major.

If you follow the arc of the handle of the Big Dipper, you’ll run in to the brilliant star Arcturus, which marks the bottom of the ice cream-shaped Bootes. Facing west, you can see the spring constellation of Leo, which is easily picked out by locating the Sickle; a group of stars that look like a backwards question mark. If you look to the south, you can see two constellations very close to the horizon; Scorpius resembles a fishhook and Sagittarius is an obvious group of stars that resembles an old fashioned teapot. (If you find the spout of the teapot, it points towards the center of our Milky Way Galaxy.)

Last but not least, when you face east, you will see a definite sign that summer is here because the Summer Triangle shines brightly in the sky. The Summer Triangle is made up of these three bright stars; Vega in Lyra, Deneb in Cygnus and Altair in Aquila.

Because the Big and Little Dippers are high overhead this month, I thought we would take a brief look at them. The Dippers are circumpolar stars, which means they are always visible in our nighttime sky no matter when you go stargazing. The Big and Little Dipper are not actual constellations but are asterisms, which means they are a well-known group of stars but not an official constellation.

Ursa Major, the Great Bear, has many myths associated with it going back to the earliest civilizations. It was envisioned as a great bear with native North American Indians and ancient Greeks. The British have referred to it as a Plough since medieval times. The Greek myth tied to the Great Bear is that Zeus fell in love with Callisto and they had a son, Arcas. Zeus’s wife, Hera, became very jealous and turned Callisto into a bear.

Ursa Major is our third-largest constellation. It’s best known for the asterism the Big Dipper. The Big Dipper is a group of seven bright stars shaped in the form of a dipper. Other than Orion; it is one of the best known star patterns in the sky.

The Big Dipper can be used to help locate other stars and constellations. Dubhe and Merak, the stars in the end of the bowl of the Big Dipper, are known as “the pointers.” If you draw a line straight through these stars and continue on northward, the next-brightest star you will run into is Polaris, the North Star. As mentioned above, if you follow the arc of the handle, you’ll run in to Arcturus. If you continue that arc you’ll “speed on to Spica,” the bright star in Virgo. If you draw an imaginary line down from the middle of the bowl you will run in to Leo. If you draw a line to Polaris from the star where the bowl connects to the handle, then continue that line you’ll find Cassiopeia,.

The second star in the handle of the Big Dipper is actually a multiple star system. They are named Mizar and Alcor that can be seen as a double star with the unaided eye. Mizar and Alcor are also known as the “Horse and Rider.” The ability to see these two stars was once used as a vision acuity test.

Ursa Major offers many nice galaxies, among them are M81 and M82, a spiral and an irregular galaxy that can be seen in the same field of view in a telescope. Another unusual deep-sky object in Ursa Major is M97 known as the Owl Nebula because it resembles a ghostly owl.

Ursa Minor, the Little Bear, has existed in mythology for centuries along with the myth concerning the Great Bear. When Arcas reached manhood, he was about to shoot a bear, not realizing it was his mother, Callisto, whom had been turned into a bear by Hera. To protect his son from the horror of killing his mother, Zeus changed Arcas into a bear and carried them both to the heavens where they became constellations. Zeus carried the bears to the skies by their tails, causing them to stretch out. Hera was outraged at the honor bestowed on Callisto and Arcas, so took revenge on them by making them never able to dip beneath the sea of stars to rest; that is why you will always see the Little and Big Bear circling forever around the north star.

Ursa Minor, the Little Dipper, also resembles a dipper, but is much less conspicuous than the Big Dipper because the stars aren’t as bright. It contains Polaris, a very important star in our skies.

Polaris is the North Celestial Pole star that always remains roughly in the same spot in the sky, while all the other stars appear to circle clockwise around it once a day. If you watch the sky all night you will see the Little Dipper rotate around Polaris. Polaris is not one of our brightest stars because it shines at only second magnitude; nor is it always the star closest to the north pole. Due to the precession, or the wobbling of the Earth on its axis; the celestial pole slowly shifts as the centuries go by, when different stars then become the north pole star. One entire precession of the galactic pole takes 26,000 years.

Some of the other bright stars that will be a Pole star are Thuban in Draco, Vega in Lyra, Deneb in Cygnus and a few stars in Cepheus. The Southern Hemisphere doesn’t really have any bright stars that are near the South Celestial Pole.

Besides Polaris, most of the Little Dipper stars are faint. Only the two stars at the end of the bowl are fairly bright. They are called the “Guardians of the Pole” as they march around the pole like sentries. The brighter star of the Guardians, Kochab, was the Pole Star at the time of Plato, about 400 B.C.

This is a monthly article provided by the Cheyenne Astronomical Society (CAS). Marcy Curran has been the editor of the Cheyenne Astronomical Society’s newsletter since 1986 and taught astronomy at LCCC from 1992-2013. For further information about the CAS, visit our website at killerrabbit.co. Our monthly meetings are free and open to the public and are held the third Friday of each month.

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