Stars Over Sisters

Slithering through the evening skies of spring is a mythological water serpent. Hydra is the largest and longest of the 88 constellations, measuring 1,303 square degrees in area and spanning almost 105 linear degrees across the celestial sphere. Except for its head, found beneath Cancer the Crab, this beast is located entirely below the celestial equator.

As evening falls during the month of April, look to the south for an irregular arrangement of six moderately bright stars that denote Hydra's head. About 15 degrees to the southeast is Alphard, the constellation's brightest star, which represents the creature's heart. From here the remainder of the constellation resides to the south of Sextans, Crater, Corvus and Virgo. An unobstructed southern horizon is required to observe the entire length of Hydra, which ends at Libra.

According to legend, Hydra was killed by Hercules as the second of his twelve labours. It wasn't easy, however, because when one of Hydra's heads was cut off, two more would grow in its place. Hercules eventually overcame the monster by burning out the roots of the heads, preventing them from growing again.

Hydra contains three very fine deep-sky objects discovered by French astronomer Charles Messier. The most prominent of these is M83, a strikingly beautiful galaxy located near the border of Centaurus. Sometimes referred to as the Southern Pinwheel Galaxy, it lies at a distance of some 15.2-million light-years and is about half the size of our Milky Way galaxy.

In roughly the same vicinity, M68 is a globular cluster made up of a tightly packed ball of older, metal-poor stars located approximately 31,000 light-years from the earth. The true splendor of this cluster is revealed through the eyepiece of a medium-sized telescope. M48 is an open cluster that is visible to the naked eye under dark skies. It contains about 80 stellar members that have been described as having a triangular shape that covers more than half a degree of sky - larger than the diameter of the full moon.

The month begins with a new moon on April 7, leading to dark skies. First quarter will occur on April 13, with the moon growing into the smallest full moon of 2016 on April 21, lying 30,000 miles further away from Earth than the closest full moon of the year in November. The month ends with the moon waning into last quarter on the April 29.

Mercury, the innermost planet, will appear low in the western sky at dusk. The best way to find it is by drawing a line through Orion's Belt toward the horizon, which will point you right to the elusive planet. The sun's glare may make finding Mercury a bit difficult, but binoculars will help you locate it an hour or so after sunset.

Jupiter will be a dazzling sight in the southern sky, joined by a waxing moon in mid-month. The giant planet will be in the sky all night, finally setting in the west in the early morning all month long.

On April 15 Mars rises above the southeastern horizon at about 11:20 p.m., followed by Saturn half an hour later. These two planets reach their peak height in the wee hours of the morning and stay up until the sun takes stage again.

To learn more about the night sky, join the Sisters Astronomy Club for a starwatch on April 30. The program will begin at 8:30 p.m. with a presentation in the Sisters Park & Recreation District building, located at 1750 W. McKinney Butte Rd. in Sisters. After the lecture, telescopes will be available for viewing the night sky in the northwest corner of the high school parking lot. The event is free.