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the eye of bull
Credit Jerry Lodriguss / NASA.gov
the eye of bull

This week Hal tells us about one of the brightest stars in the sky, a red giant by the name of Aldebaran.

I’ll warn you up front, this episode has a lot of bull. Because this week, we’re talking about the remarkable star Aldebaran, which forms the red eye in the constellation Taurus the Bull. Aldebaran rises in the East shortly after Sunset and is visible all night long. It’s easy to find. Draw a line through the belt in the constellation Orion, up and to the right and you will hit Aldebaran.

Aldebaran is one of the brightest stars in the sky; there are only 13 that are brighter. But the reason Aldebaran is so bright is why it is so interesting. As stars go, measuring light generated per unit of surface, Aldebaran is fairly dim. Its surface temperature is thousands of degrees cooler than our own Sun. And because it’s cooler, it glows red.

But if it’s cool, why is it so bright? Because it’s absolutely huge! It’s a monster star. Our Sun is big – you could put 1.3 million Earths inside it. But Aldebaran is far larger. If Aldebaran on was the size of a softball, our Sun would be about the size of a pea.

At only 65 light years away, Aldebaran is basically a neighbor. And Aldebaran is not alone out there. It has a companion star orbiting it. This tiny, red dwarf star is 3 ½ light days away from Aldebaran. In our own solar system Pluto, which seem so unspeakably distant from the Sun, is only 5 ½ light hours away. Gravity is amazing.

And, Aldebaran is old, and things are going well. It’s already burned through its supply of hydrogen, and is now fusing helium into carbon. So be sure and take a good look at Aldebaran, as it may be gone in a few million years. No bull!

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

This is Hal Bidlack for the Colorado Springs Astronomical Society, telling you to keep looking up, Southern Colorado!