Stars over Sisters

In past articles the authors of this column have guided watchers of the night sky to various constellations that populate the celestial sphere. By simply following the directions, readers were led to a collection of stars that comprised a particular constellation. This exercise was made easier when the targeted stars are bright.

Identifying this month's featured constellation, however, may be a bit more difficult. Canes Venatici represents the two hunting dogs of Bootes the Herdsman. Asterion, the northern hound, is denoted by the star b Canum Venaticorum, while the southern hound, Chara, is marked by Cor Caroli, the constellation's brightest star. Canes Venatici is bordered by Ursa Major to the north and west, Bootes to the east, and Coma Berenices to the south. It lies directly beneath the handle of the Big Dipper.

Cor Caroli is one of the finest double stars in the sky and is famous for the subtle hues of each of its two stellar components. Many credible observers have reported seeing a wide range of colors, including "pale yellow and fawn" and "flushed white and pale lilac." Others have described the dimmer secondary star as "pale olive blue" and "pale copper." Cor Caroli is easily split by even small backyard telescopes, so take a look for yourself. What colors do you see?

Though Canes Venatici is devoid of bright stars, it contains a wealth of deep-sky objects. Many of them are relatively bright galaxies, the most prominent of which is M51, the famous Whirlpool Galaxy. M51 is a large face-on spiral galaxy located about 37-million light-years from Earth.

This is an active galaxy that contains many star-forming regions and nebulae in its arms. In June of 2011 a bright supernova erupted in this galaxy that was seen by a number of amateur astronomers in the local area.

A total lunar eclipse will occur in the early morning of April 15. Totality begins at 12:08 a.m. and ends at 1:23 a.m. PDT. Then, on October 8, the second total lunar of the year will also be visible from Central Oregon. A lunar eclipse occurs when the earth's shadow falls upon the full moon.

Mercury languishes low in the eastern sky, all but lost in the light of dawn. The planet will draw nearer the sun throughout the month. On April 25, it will slip behind the sun and emerge as an evening object in May.

The brilliance of Venus continues to dominate the pre-dawn sky during April, rising in the east about an hour and 45 minutes before the sun.

The earth is rapidly gaining ground on Mars, and on April 8 the sun, the earth and Mars will align in a configuration called opposition. This is the best time to view the Red Planet because it will be relatively close to the earth, and will rise as the sun sets and be visible all night long.

Although Jupiter is now confined to the western sky by nightfall, it still presides over evening's stellar realm. Throughout the month the largest planet in the solar system will continue to slowly slip lower in the west, and by month's end will set about 1:20 a.m.

Saturn rises before 10 p.m. by mid-month, and in early May will be well placed to observe its stunning ring system. The moon progressively becomes brighter during the first half of the month, then gradually darkens thereafter. Our only natural satellite is at first quarter on April 7, full on April 15, last quarter on April 22, and new on April 28.

If you wish to learn more about the night sky, you are invited to attend the first Stars over Sisters star watch of the season on Friday, April 25. A pre-star-watch presentation will be held at the Sisters Park & Recreation District's Coffield Center office beginning at 8 p.m. Following the talk, visitors will have the opportunity to view the night sky through telescopes provided by members of the Sisters Astronomy Club. The event is free.