Saturday, May 23, 2009

Scorpio and Orion

According to Greek Mythology, Orion was a great hunter who angered the gods with his prowess. Being Greek and touchy, they sent a scorpion after him as revenge. The story goes that Orion is perpetually avoiding the scorpion, so that the two are never in the sky at the same time- Orion always sets before the scorpion rises, and refuses to reappear until the Scorpion is gone.

The reason this works for the Greeks is that Scorpio is a Southern Hemisphere constellation. From the northern midlattitudes, it is only visible for 9-10 hours a night, so there is ample time for a gap before and after Orion. Down here in Australia, though, the opposite is true. Scorpio stays up for 13-14 hours, so there is a window where both Scorpio and Orion can be seen low on opposite horizons. This is most easily seen around this time of year, when Orion sets early in the evening, and Scorpio rises right around sunset.

I few years ago, I took a picture of this, but never got around to blogging it. So here they are:
Orion diving into the last glimmer of twilight in the west, while in the East:

Scorpio rises over downtown.