A star that would give you a nasty sunburn snuggles close to the Moon early tomorrow. They're low in the east at first light. The star is to the left or lower left of the Moon, by no more than the width of a finger held at arm's length.
The star is Regulus, the "heart" of Leo, the lion. And as befits the king of the beasts, it's a strong heart indeed: The star is more than three times wider and more massive than the Sun.
Because of its heft, the star's core "burns" through its hydrogen fuel in a hurry. That heats up the star's outer layers, so they glow white hot -- an indication that the surface of Regulus is thousands of degrees hotter than the Sun.
Thanks to its temperature and size, Regulus shines more than a hundred times brighter than the Sun. But that's only in the wavelengths of light that are visible to the human eye.
Because Regulus is so hot, much of its energy is in the form of ultraviolet radiation. It's not visible to the human eye, but you can certainly feel its effects -- it's the type of energy that gives you sunburn.
Earth protects us from the Sun's ultraviolet energy with a layer of ozone at the top of the atmosphere. But to provide the same level of protection at Regulus, a planet would need a much thicker ozone layer, and it would need to be a good bit farther out than Earth is from the Sun. And even then, you might still want a thick slathering of sunscreen to protect you from the heart of the lion.
Script by Damond Benningfield, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.