Sagitta – the arrow

October 30, 2016

Astronomy

sge_03Sagitta is a tiny constellation whose dots actually connect to make an arrow, complete with fletching feathers. It’s one of the older names for a group of stars but then the bow and arrow as a weapon goes way back, probably invented more than 60,000 years ago. So the constellation must have been named sometime after that. Ptolemy included it on his maps 2000 years ago.
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The story goes that the arrow is being fired from the bow of Hercules, who is suspiciously standing nearby. He is taking a flock-shot at three birds, the Eagle (Aquila), the Swan (Cygnus), and the Harp (Lyra). Okay the harp is actually a musical instrument but at one time the Greeks thought it was a vulture. It occurred to me that Herc might really be aiming just at the swan because eagles and vultures probably taste like crap. But sifting through the various stories suggest that more likely he is shooting at the eagle because it is chewing on his buddy Prometheus’ liver. With Greek mythology the sickest answer is usually correct.
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As you may recall, the eagle is punishing Prometheus for teaching humans how to make fire. So a much more poetic solution would have been for Hercules to set the eagle on fire.

bow-and-arrow-5The pointy tip of the arrow is Gamma Sagittae, the brightest star of the group. It’s a red giant, cool on the surface but with a core that is among the hottest places in the Universe, much like a burrito fresh from the microwave.

Just off to the side of the arrow you will find WR-124, a Wolf-Rayet star. These types of elderly stars can put out unusually high amounts of ultraviolet light, so your old day-glo Jimi Hendrix posters would glow very brightly there. Nearby is the star FG, which is poorly behaved. It has changed size and color several times since it was first discovered in 1943.

m71There is a globular cluster to be had here, M71, so don’t miss out on that. Sure it’s not as spectacular as a real show-stopper globular, like M13 or Omega Centauri for example, but hey a globular is a globular. It’s hard to go wrong with a globular. Everyone loves a globular. It’s not even a party without some good globular.

Out of the 88 constellations Sagitta is the 86th smallest so you might think it is easy to overlook. But it stands out pretty good where it is situated. Many times people have asked me “What’s that little one there that looks like an arrow?” I typically respond with “Oh you mean that one there in the fourth quadrant of the northern hemispere that can be seen at latitudes between +90° and -70°, from every location on Earth except the Antarctic circle?” That usually shuts them up and I can go back to looking at globulars.

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Carpe Noctem.

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