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Venus and Aldebaran

July 6, 2012

We all know that those little twinkling lights in the night sky are stars — brilliant balls of hot gas seen from a great distance. Even so, it’s hard to comprehend just how far and how bright they really are.

One way to get a handle on it is to compare a star to something that’s right next door. And there’s a good opportunity to do just that the next few mornings.

The planet Venus is fairly low in the east at first light, shining as the brilliant “morning star.” The slightly fainter planet Jupiter is above it. But a true star is just below it — Aldebaran, the orange “eye” of Taurus, the bull. It doesn’t look as impressive as the two planets, but that’s only because of its great distance.

Aldebaran is a stellar giant — it’s puffed up to many times the diameter of the Sun. That makes it exceptionally bright. To understand just how big and bright, compare it to Venus.

Right now, the planet is about 38 million miles away. Aldebaran is 10 million times farther than that. If it were the same distance as Venus, it would span a third of the sky, and its surface would stretch halfway to Earth. Most impressive of all, Aldebaran would shine about a million million times brighter than Venus.

Fortunately, we’ll never get that close to Aldebaran — all that energy would incinerate Earth. But in a few billion years, Earth will experience a similar view — as our own star, the Sun, swells to the same giant proportions as the bull’s bright orange eye.


Script by Damond Benningfield, Copyright 2012


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