There's an extra star in the sky tonight.

Hard to believe anyone can tell. But, in fact, this one's pretty easy to spot. Its name is Mira, and it's what astronomers call a long-period variable.

OK, so it's not really a "new" star, but it's one that we haven't seen for nearly a year. You see, Mira pulsates in brightness over about 11 months — becoming about as bright as the North Star and then fading well beyond naked-eye visibility. Right now, it shines near its brightest and outshines all but one star in its celestial region.

German astronomer David Fabricus, who had been searching for the planet Mercury, found the star a little more than four centuries ago. Instead he found this peculiar star that appeared nowhere on his star catalogues, atlases or globes.

A few months later, when he looked for the star in the sky, it wasn't there either. Then, on February 16, 1609, there it was again.

Not until 1660 did astronomers realize that this strange star had been there all the time, but that it varied in brightness over a period of 11 months. Mira, also known as Omicron Ceti, became the first star ever discovered to change its brightness and soon became known as Mira the Wonderful.

Modern astronomers know that, not only does Mira's brightness vary, but so does its size. Though we cannot see this with the naked eye or even a telescope, astronomers have calculated that its orb swells and contracts by about 20 percent. At its largest and brightest, the star is more than 300 times larger than the sun. That means that, if it replaced the sun in our solar system, its glowing atmosphere would swallow the orbits of Mercury, Venus, Earth, and Mars, and would extend halfway to Jupiter.

If that weren't enough, in 2007 astronomers discovered that Mira has a strange comet-like tail about 13 light-years long — possibly formed out of material ejected by the star during the past 300 centuries.

Just after dark this week this remarkable star shines at its brightest. In the southern sky lies the constellation Cetus, the sea monster. Think of its head on the left and its body on the right, connected by a long neck. And there, in the middle of Cetus shines the unusual star known as Mira the Wonderful.

To find out more about Dennis Mammana and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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