Week of Jan. 29-Feb. 4, 2017
There will soon be an extra star in our nighttime sky.
It's hard to believe that anyone can even tell, but actually, this one's not too hard to spot. Its name is Mira, and it's what astronomers know as a long-period variable star.
OK, so it's not really a new star. But it is one that we haven't seen for a while. You see, Mira pulsates in brightness, becoming easily visible in the sky and then fading well below naked-eye visibility.
The star was found little more than four centuries ago by German astronomer David Fabricius. He had been searching for the planet Mercury, but instead, he found this peculiar star that appeared nowhere in his catalogues, atlases or globes.
A few months later, when he looked for the star in the sky, it was nowhere to be found. Then, on Feb. 16, 1609, there it was again.
Not until 1660 did astronomers begin to realize what was happening. The star had been there all the while, but it varied in brightness over a period of eleven months. Mira, also known as Omicron Ceti, became the first star ever discovered to change its brightness.
The name "Mira," which contains the Latin root for such words as "miracle," means "wonderful." And its discovery was rather wonderful as well, since it supported the intellectual revolution begun by Copernicus a few decades earlier. He said that the heavens were not unchangeable. No wonder it soon became known as Mira, the Wonderful.
Today we know Mira as the most famous of all long-period variable stars. It begins its cycle about as bright as the North Star, fades by more than 600 times and then brightens again, all during a period of 332 days. Soon it should shine near its brightest and outshine all but one star in its celestial region.
Perhaps even more interesting is that not only does Mira's brightness vary over time 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. This means that if it were to replace the sun in our solar system, its glowing atmosphere would swallow the orbits of Mercury, Venus, Earth and Mars, and would extend part of the way to Jupiter.
Astronomers have also discovered that Mira has a strange cometlike tail about 13 light-years long, possibly formed out of material ejected by the star during the past 300 centuries.
After dark this February, you should be able to spot this wonderful star near its brightest. In the southwestern sky lies the constellation Cetus, the sea monster or whale. Cetus is said to be the beast that Poseidon sent to plague Cepheus when Cassiopeia claimed to rival the Nereids in beauty. It was placed in the heavens to commemorate his heroic deed.
With some imagination, one might almost be able to make out the whale's huge body and its tail stretching upward. And there, in the middle of Cetus, shines the peculiar star Mira, the Wonderful.
Visit Dennis Mammana at www.dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.
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