The Nautical Almanac # 49 --- Vega, the Stooping Raptor

Vega has been called "the second most important star in the sky" after the Sun. If stars were numbered by reputation in the Nautical Almanac Vega would be listed first after Polaris (number 0); however Vega is the forty-ninth numbered star on the list. 

Vega, "The second-most important star in the sky."

Vega is the brightest star by far in the small constellation of Lyra The Lyre (or Harp), and rings in at Magnitude Zero. When the Magnitude scale was formalized, Vega was the benchmark star. It is, in reality, only the fifth-brightest star in our skies, and the second-brightest in the Northern Hemisphere after Arcturus. However, it gleams with a unique bluish-white glow that makes it different from all other stars that humans can see. Vega's remarkable color comes from an almost complete lack of elements heavier than helium in its chemical make-up. 

The gas cloud around Vega, with planets and planets a-borning.

 

An artist's representation of Vega, surrounded by a dust cloud, asteroids, a terrestrial planet, and an ice giant with rings.

In many modern languages "Vega" means "Star", but its name "Wega" (pronounced "Vee Gah"), goes back to Mesopotamian days, and means "Swooping". To people who came before the Greeks Lyra was not a harp but a vulture or an eagle stooping on its prey. Vega was also a "feminine" star, as raptors in flight with outspread wings were representative of women (as opposed to men, who were represented by the many serpentine constellations). To the Greeks, however, Lyra was the harp of Orpheus, and represented Man's first musical instrument. The Romans took its setting as the moment their Autumn season began. 

Vega was the Pole Star in those long-ago years when human civilizations were developing in the Tigris-Euphrates, Nile, Indus, Hwang Ho, and Mississippi river valleys, and as such it was the centerpoint of early human cosmology. The most ancient astronomical monuments we have been able to discover were built in reference to Vega. Vega was Tir-Anna ("The Life of Heaven"), Dayan-Sama ("The Judge In Heaven"), and Dilgan ("The Angel of Light") to the various Mesopotamian peoples. To the Egyptians Vega was the god Ma'at, the giver of justice and order. 

It is the 14th of the fifteen Behenian Stars and according to Hermes Trismegistus it protects against demons, nightmares, and daytime terrors. It also gives the querent the ability to commune with animals. 

The Chinese have a charming legend that Vega (the girl) and Altair (the boy) were forbidden to marry by the girl's father (Deneb) who kept them apart. These three stars make up the asterism known as the Summer Triangle. Interestingly, the two other constellations involved in the Triangle are Cygnus The Swan and Aquila The Eagle; if Lyra is seen (as it once was) as The Vulture, that would make three avian constellations.

Hindu mythology speaks of the sky god Abhijit who "slipped down in the sky" after a contest with the other gods, probably because the Pole moved away from Vega over time. Due to precession, the wobble of the Earth on its axis, the Pole shifted to Polaris about 7,000 years ago, but in another 12,000 or so years Vega will again be the Pole Star (the precession cycle takes roughly 26,000 years).

Scientifically, Vega is no less interesting. In 1843, it was the first star whose size and distance were calculated. In 1850, it was the first night star to be photographed. It was the first star (aside from the Sun) studied via spectroscope (1872). In 1979, scientists studying Vega discovered for the first time that stars could emit X-Rays. In 1983, it was the first star recognized to have a dust and gas cloud around it, an indicator of planets and planetary formation (the cloud has been photographed, below). 

Vega is thought to have at least one Neptune-sized gas giant in orbit around it, and a number of terrestrial planets or planetesimals that are in the process of forming planets (an artist's representation is below; note the shape of Vega). 

Carl Sagan popularized Vega on his TV show, "Cosmos," and it was the first star to have a car named after it (the Facel Vega of 1954 in France, and the Chevrolet Vega of 1971, in the U.S.). Vega appears frequently in science fiction. 

Vega is relatively close to Earth, at only 25 light years away. Vega is twice the mass of the Sun, and two-and-a-half times the radius of the Sun. Vega is about a half a billion years old, and is considered middle-aged. 

Vega is a Main Sequence star. It rotates very rapidly; where the Sun turns on its axis about once every 28 days, Vega spins like a top at 50,000 miles per hour, completing one rotation in 12 hours. This means that Vega is very oblate, flattened at the poles and bulging at the equator. Scientists believe that Vega is just barely holding itself together. At the poles, Vega's temperature is 17,600 degrees Fahrenheit, but at the equator only 17,000, a significant difference that indicates how tenuous Vega's shape is. It is also brighter at the poles (40 times the Sun) than at the equator (38 times the Sun), and since we see Vega North Pole-on, we are seeing Vega at its brightest.