Friday, November 2, 2012

DRACO, THE DRAGON IN THE SKY

In my opinion, Draco is one of the only constellations that actually looks like what it's supposed to be.  Or at least it does if you think of dragons as looking like snakes.  Of course, the Big Dipper and the Little Dipper look pretty much like dippers, but they don't look like bears, which is what they are called in Latin.

Illustration from Hyginus, 1498


One thing that makes Draco interesting is that it is so far north in the sky that it can be seen all year round if you live in the northern hemisphere.  But if you live someplace like New Zealand, you will never, ever get to see Draco, so you will just have to be happy with your own constellations.




The Greek astronomer Ptolemy was the first person to chart Draco, and he did that in the 2nd century.  The constellation's name comes from the Latin draconem, which means "huge serpent."  Ptolemy made a list of 48 constellations.  Nowadays, we have 88 constellations, and Draco is still on the list.




The Ancient Egyptians called the constellation Tawaret, which was the name of a goddess whose body was shown in pictures as part human, part lioness, part crocodile, and part hippopotamus.  The pyramids in Egypt were designed so that the doorway was facing the North Star.  This is not the same star we call the North Star today.  Instead, it was a star named Thuban, which is one of the stars in Draco.


Picture of Tawaret by Jeff Dahl

You might be thinking that the Egyptians made a mistake when they were figuring out which star was the polar star, but they didn't.  Back then, in 3000 BCE, Thuban really was the North Star.  What happened since then was something called precession, which means that the tilt of the earth changed a little bit.  Someday it will change back, so by 21000 CE, Thuban will be the Pole Star all over again!


Thuban is that red star over on the right side

Draco is the eighth-largest constellation.  Its stars are not very bright, but at least five of them have planets.  Draco also has several double stars, binary stars, interacting galaxies, and galaxy clusters.  I am not an astronomer, so I don't know what some of this stuff is, but I figure that if you really want to know, you will go look it up yourself!

The coolest thing that Draco has is the Cat's Eye Nebula.  This nebula was discovered back in 1786 by an English astronomer named William Herschel.  When the Hubble Space Telescope looked at the nebula, everyone thought it looked like a cat's eye, so that's how the nebula got its name.


NASA photo

In Greek mythology, there were several dragons, and some of them might have ended up in the sky as Draco.  For example, the Olympic gods spent ten years fighting the Titans, and one Titan was called Draco.  Finally, the goddess Minerva managed to throw Draco up into the sky, and he froze in a twisted-up shape.

There was also a dragon named Ladon who had 100 heads and who guarded the golden apples of the Hesperides, who were the nymphs of the evening.  These apples were special because if you ate one, you could live forever.  One of the 12 labors of Hercules was to steal the golden apples, which he did by being very clever and lulling the dragon to sleep with music.




Draco may also have been the dragon that Jason killed so he could get the Golden Fleece.  And then there is the story of Cadmus, the Prince of Phoenicia, who had to kill a dragon before he could found the city of Thebes.  The early Christians said that Draco was the serpent from the Garden of Eden, who talked Eve and Adam into eating the apple.  So in mythology, poor Draco was always getting a bad rap or getting killed.

Draco and Ursa Minor, from a set of constellation cards,
published in London, 1825

But guess what!  The Arabs did not see the constellation as a dragon or a serpent.  Instead, they called it the Mother Camels.  There is a whole story connected with this, where two hyenas start attacking a baby camel, and four female camels protect it.

Anyway, that's all I'm going to tell you about Draco the Dragon or the Mother Camels or whatever shape you think it is.  But I will say that this all goes to prove that any time you start looking for pictures in the stars, you are likely to see almost anything.  And unless you are lying flat on your back, you are also likely to get a crick in your neck!


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