Category Archives: Astronomy

May the great stars of the night, Shining Fire-Star, heroic Irra, Bow-star, Yoke-star, Sitaddaru, Mushussu-star, Wagon, Goat-star, Goatfish-star, Serpent-star, stand by and put a propitious sign on the entrails of the lamb I am blessing now.
(Old Babylonian prayer, from Ancient Astrology by Tasmyn Barton)

Canopus: the brightest star you’ve never heard of

Ever since I wrote a post on Polaris, I have been wondering, is there a south pole? Sadly, there isn’t, not really.

There are two candidates for a south pole star. By 14 000 CE Canopus will, because of the wobble in the earth’s axis, be as close as it will ever get to being the South Pole, about 10° from magnetic south. The other, Sigma Octanis in the Octant, is the closest star at present. The Southern Cross points to where a south pole would be, and like Ursa Minor is a circumpolar constellation, so it’s always above the horizon.

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Deneb: swan’s head

Like the eagle in Aquila, the swan is a bird with many associations, so it seems logical to put a swan in the sky. It was Venus’ bird; the Romans sometimes called the constellation Myrtilus because of this, myrtle also being Venusian.

The Greeks, however, assigned the swan to Apollo, who had a team of them to pull his chariot. Zeus also assumed the shape of a swan to rape Leda, the queen of Sparta, who then gave birth to the Dioskouroi (and in some versions, Helen and Clytemenestra) in an egg, which must have been rather uncomfortable for her. Continue reading

volcano wallpaper

Vulcan: the planet that never was

This blog has frequently lamented the demotion of Pluto. After being expelled from the company of planets, it now resides in the newly-named Plutoids, in the company of Eris, Sedna and other dwarf planets. Another one-time planet suffered a worse, and lonelier, fate one hundred years ago.

The planet Vulcan came into (theoretical) being as a solution to the problem of Mercury‘s orbit, which deviated from the track that Newton’s laws laid down for it. Continue reading

Altair: the Eagle

Eagles and thunder-gods often appear together, but in Greek myth the eagle was Zeus’ accomplice as well as his emblem. It stole the beautiful youth Ganymede from his fields and carried him to Olympos to be Zeus’ cupbearer. (Ganymede is also in the heavens, as the constellation Aquarius.)

The eagle also carried out Zeus’ punishment of Prometheus, who stole fire to give to the humans. Zeus had him chained to a cliff face, and the eagle came every day and tore out his liver. Hercules rescued Prometheus as part of his 11th Labour and killed the eagle. Zeus then put it in the sky to reward its faithful service.

The Eagle features among the Hercules family of constellations, by the way, which include large asterisms like Ophiuchus the Snake-Handler as well as tiny ones like Ara, the Altar.

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Vega: the jewel in the Harp

Vega is the fifth brightest star in the sky, a brilliant blue-white star two and a half times larger than the sun. It takes turns with Polaris and Thuban as the pole star, and will be the nearest star to the celestial north pole again in 14 000 AD.

It lies in the constellation Lyra, and in the northern hemisphere you can see it from the middle of May onward. Its culmination is on July 1st. (The constellation was also known in ancient times as the Vulture, and the star’s name comes from the Arabic waqi, “swooping, falling”.)

Vega has an asteroid belt around it, which has excited speculation that it might have its own planets. It has always attracted attention because of its brightness, and was the first star other than the sun to be photographed, at the Harvard Observatory on the night of July 16-7, in 1850. Continue reading

Aldebaran: the Bull’s Eye

As you can see from the picture above, Aldebaran is the bull’s left eye, and the brightest star in Taurus. It appears ruddy through a telescope, suggesting that Taurus is an angry bull. The V-shape of the bull’s face, known as the Hyades, makes it easy to find.

The Arabic name reflects its position: the Follower, since it rises after the Pleiades, the stars that make up the bull’s shoulder. It is primarily a winter star, and by now will be visible in the sky around dawn.

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Fomalhaut: the Fish’s Mouth

Fomalhaut was one of the four year-stars. Since the other three belong to the “fixed” astrological signs Taurus, Leo and Scorpio, Fomalhaut is assumed to be associated with Aquarius, the fourth fixed sign. It can be seen low in the southern sky in the fall, and can be seen due south around 11:00 p.m. in early October.

However, this star actually belongs to Piscis Austrinis, the Southern Fish. Not be confused with the nearby constellation of Pisces, this fish rests below the water-bearer’s foot.

Its name comes from the Arabic for Fish’s Mouth, from its position in the constellation. The water Aquarius pours out seems to fall directly into this area, which led to astronomers incorporating the Fish into Aquarius. This area of the sky is called the Sea, since it contains Cetus, the Sea-Monster, Aquarius, Piscis Austrinis and Pisces.

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