Looking Up: Wasat An Innie Or An Outie?

Dec 18, 2017

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This week on Looking Up Hal answers the question that everyone tends to ask at some point in their life - "what's that?"

Our astronomy club does a large number of public star parties over the course of the year, and it is very common for a person at one of our events to point to a star in the sky and ask, “what’s that?” Well, this week, I’m going to tell you about a star that is a great answer for the question “what’s that?' -  the star Wasat.

Credit WIKIMEDIA COMMONS

You likely have heard of the famous twin stars, Castor and Pollex that make up the “heads” of the twins in the constellation Gemini. But I’m betting you haven’t heard of the star that makes up the belly button of the Pollux twin, the interesting star Wasat. Wasat is special not so much because of what it is, but more where it is. As it turns out, Wasat sits only 2/10th of a degree off the plane of the ecliptic – the plane in space that all the planets are in as they orbit the Sun. That means that every now and then, the Moon, or a planet, passes directly in front of Wasat, blocking or “occulting” it momentarily. Now, you may say to yourself that Pluto isn’t in the same plane as the other planets, and that is true. But, my friends, Pluto isn’t a planet, in part because of its weird orbit. Interestingly, Pluto was actually discovered in 1930 very near Wasat, which also marks the point in the sky where Pluto passes through the ecliptic as it travels though the Solar System, making Wasat a very well-placed star. So if you are flying to another planet, or even Pluto, keep an eye on Wasat, it will help you find your way.

If you’d like to take a closer look at Wasat or any of the other wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.