Stars over Sisters

Our expansive night sky holds many prominent constellations. Most, however, can only be seen during certain times of the year. Such is not the case for the featured constellation this month.

Ursa Minor, also known as the Smaller Bear, or the Little Dipper, is a circumpolar constellation when viewed from the mid-latitudes in the northern hemisphere. This means that the stars that comprise Ursa Minor never set below the horizon. In fact, the north celestial pole itself resides here.

To many stargazers, Ursa Minor has the appearance of a frying pan sitting high in the northern sky. This constellation should not be confused with the more prominent Ursa Major (Big Dipper). Both share the same famous frying pan appearance, except Ursa Minor is much smaller in size.

Polaris, or the North Star, is the brightest star in the Little Dipper. It marks the end of the "panhandle" or the tip of the Smaller Bear's tail. It is a multiple star consisting of three different-sized stars. Two of these stars are easily visible through small backyard telescopes. Although Polaris is an important guide star in celestial navigation, it is not one of the brightest objects in the night sky.

While Ursa Minor does not contain many deep-sky objects, one of them is an interesting barred spiral galaxy that displays an active galactic nucleus. It is relatively small, only about a third the size of our Milky Way galaxy and lies about 60-million light years distant.

Greek mythology reveals that Arcas was the son of Zeus, god of gods, and Callisto, a most beautiful nymph. When Hera, Zeus' wife, got wind of this, she became jealous and transformed Callisto into a bear. While out hunting one day Arcas came across a large bear. Not knowing it was his mother, Arcas was preparing to kill her with an arrow. To avert the impending tragedy, Zeus placed them in the heavens as the big and little bears. Hera was against this honor and took action by convincing Poseidon to forbid them from bathing in the sea.

It is for this reason that the constellations of Ursa Major and Ursa Minor never dip beneath the horizon when observed from the northern latitudes.

Although comet PanSTARRS continues to dim as it heads back to the outer regions of the solar system, it is still visible through binoculars or a telescope. Look to the northwest after sunset.

Located in the constellation of Taurus, the planet Jupiter is still the brightest object in the night sky. Saturn is currently in Libra and will achieve opposition on April 28. This means the planet will rise as the sun is setting and be visible all night.

The lunar cycle in April begins with the last quarter moon on April 2. The moon is new on April 10. First quarter occurs on the 18th; the moon will be full on

the 25th.

The first Stars over Sisters star watch of the 2013 season will kick off on Friday, April 12 at Sisters Park & Recreation District (SPRD) beginning at 8 p.m. Then on Saturday, April 20, the Sisters Astronomy Club will conduct activities associated with National Astronomy Day, again located at SPRD. The afternoon session will go from 1 to 4:30 p.m. Then later that evening a lunar star watch will take place at SPRD starting at 8:30 p.m.

For more information Ron Thorkildson at 541-549-8846.