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Moon and Spica

March 8, 2015

You wouldn’t want to come between the two giant stars of Spica, the brightest point of light in the constellation Virgo. Without strong shields to protect you from them, you’d probably be vaporized.

Spica is easy to spot tonight because it’s quite close to the right or upper right of the Moon as they rise in late evening.

Spica consists of at least two stars. Their surfaces are separated by only a few million miles, though, so their light blurs into a single pinpoint even when viewed through the largest telescopes. At such close range, the mutual gravitational pull of the two stars causes them to bulge toward each other, so each is shaped a bit like an egg.

Both of these stars are much bigger, brighter, and heavier than the Sun. They’re also much hotter than the Sun. Hot stars produce most of their energy in the ultraviolet — wavelengths that are invisible to human eyes. Ultraviolet is much more damaging than visible light, so it vaporizes any solid objects that are close to the star.

And just to make things even more unpleasant, both stars produce strong “winds” of superhot gas. The winds collide, producing torrents of X-rays — radiation that’s even deadlier than the ultraviolet.

So if you ever find yourself in the neighborhood, be sure to stay a few hundred million miles away from these amazing stars. It’s the only safe place to be.

Tomorrow: Pushing the intergalactic frontier.


Script by Damond Benningfield, Copyright 2015

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