Caveat: Where to Go When You Visit Alioth

Alioth is a star in the big dipper, also called Epsilon Ursae Majoris, and one of the 50 brightest star in the night sky.  Apparently, someone has managed to create a rough "map" of this star – meaning of its surface, I guess – despite the fact that it is more than 80 light years distant from Earth.  This is possible because of the peculiar fact that the star's strong magnetic field's poles are at 90 degrees to its axis of rotation, meaning that the magnetic pole and the distortions it causes in the spectral make up of the star's surface swing past the Earth's vantage point with the interval of the star's spin.  This allows astronomers to create a map of the different elements that compose the star's surface (which is irregular partly due to the strong magnetic field), as they swing past their viewpoint. 

I like the idea that we can make a map of something so far away, just based on deductions from viewing the spectral lines.  And once we have a map of something, we can write a tour guide, and tourists can't be far behind, right?  Let's all go to Alioth for the summer!

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