Stars Compete with Mars in the Night Sky

As Mars begins to fade, the distance between Earth and the red planet increasing, the night once again belongs to the bright stars of summer. There are quite a few bright jewels in the skies and we will talk about two of the more interesting this week, Capella and Vega.

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It is interesting that Capella was often mistaken for Mars when the observer didn't know their directions. Capella, is a brilliant yellowish star rising in the north northeast after sunset. In fact, of the ten brightest stars from mid northern latitudes, Capella is the one closest to the north celestial pole.

Capella resides in Auriga, the Charioteer, a constellation of mixed heritage. Greek and Roman tales made Auriga a legendary trainer of horses as well as having invented the four horse chariot. Arab countries however saw this group of stars as a goat herder. Capella itself was called the "Goat Star" and the three stars forming a triangle beside Capella were called "the kids."

A few old star charts show a combination of these two myths. They depict Auriga as holding a whip in one hand, as a charioteer, but also holding a she-goat (Capella) and her three kids in the other hand.

Capella measures 16 times as large in diameter as our Sun, 174 times as luminous, and is located 42 light-years away. It is part of a multiple star system, interestingly containing at least four stellar components.

The second star is an easy one to find because after dark it is standing almost directly overhead. This is the beautiful blue-white star Vega, residing in the constellation Lyra the lyre, an instrument like a harp. Vega is the third brightest star seen from mid-northern latitudes, behind Sirius and Arcturus.

Vega is the brightest of the three stars forming the large "Summer Triangle" consisting of Vega, Altair and Deneb. Vega is 25 light years away, has a diameter approximately three times that of our Sun and is 58 times more luminous.

In 1983 Vega was observed to have large dust particles around it. Astronomers thought this could well be debris related to planet formation. In January 2002, astronomers at Harvard took another look at Vega and observed actual features in the dust cloud they believed could be planets.

The stars that make up Lyra form a parallelogram with a triangle attached to its northern corner. Vega forms a point on the triangle. If you have dark skies and good eyesight, try taking a look at Epsilon Lyrae, near Vega. Your eyes might be able to pick out that Epsilon is actually a pair of stars. Binoculars will easily show them as a pair.

Another Lyra star, Sheliak is also interesting. Every thirteen days this Sheliak reduces its brightness by half when it is eclipsed by a dim companion star.

If you have a telescope (with at least a four inch mirror or lens) there is a must-see in Lyra. Between Sheliak and Sulafat lies the famous Ring Nebula, glowing like a celestial doughnut. A telescope will reveal a ghostly ring around a star. Millions of years ago this star went nova, exploding and hurling its gasses outward. The dim remnants of this star can just be seen through the wispy gasses.

Stars Compete with Mars in the Night Sky

Constellations

The Solar System