Stars over Sisters

As night falls during March, the constellation Canis Minor, the Little Dog, is positioned nearly due south. It is not far from Canis Major, the Great Dog, and Orion, the celestial Hunter. Canis Minor and Canis Major were Orion's hunting dogs.

Canis Minor is a very small constellation consisting of only two bright stars. The brighter star, Procyon, is the seventh-brightest star in the sky and is the eastern-most member of the Winter Triangle. Betelgeuse in Orion, and Sirius (the brightest star in the entire sky) in Canis Major, denote the other two corners of this large triangle.

To find Procyon, one simply needs to draw a straight line eastward across Orion's shoulders until the next bright star is encountered. From here draw another line southwestward to Sirius (very bright-you can't miss it).

Knowing that these stars form a triangle helps to locate both the stars and the constellations in which they reside.

Procyon is actually a double star. Its companion is a white dwarf, very dense but also very faint. Because the two stars are separated by just five seconds of arc, the much-dimmer white dwarf is overwhelmed by the glare of the primary and can only be seen through large telescopes.

In 2012, a planet six times more massive than Jupiter was discovered orbiting an orange star in Canis Minor. The star, HD 66141, has about the same mass as our sun, but is 174 times brighter and 1.8 billion years older and lies at a distance of about 264 light-years.

Although the Milky Way passes through Canis Minor, very few deep-sky objects are found here. The most notable exception is NGC 2508, a lenticular galaxy discovered by William Herschel in 1784. Based on how rapidly the object is moving away from the earth, the galaxy is estimated to be about 205 million light-years away.

Jupiter is the brightest object we will see in the sky this month, aside from the sun and moon. It comes out at dusk and shines in the sky until the early morning. To find the giant planet, draw a diagonal line through the two brightest stars of Orion-the right knee star, Rigel, and the left shoulder star, Betelgeuse. Jupiter is to the upper left of Orion in the constellation of Gemini.

Mars rises in the east by late evening. It is in the constellation Virgo, near the bright star Spica. Venus come up in the early morning and is only visible for a few hours before sunrise.

Located in Libra, Saturn rises at about 1 a.m. and is visible for the remainder of the night. Although hugging the southeastern horizon, Mercury will be visible in the morning sky just before sunrise throughout the month of March.

Spring arrives at 9:59 a.m. PDT on March 20. At that time the sun will be directly above the equator as it continues its northward journey that began back on December 21 of last year. When the sun is at this position, called the vernal equinox, the periods of daylight and darkness over the earth are nearly equal.

The lunar cycle this month features two new moons. The first occurs on March 1, the second on March 30. In between, the moon is at first quarter on March 8, full on March 16, and last quarter on March 23.