‘Supermoon’ will rise tonight, but don’t get too excited

March 19, 2011

Eye on Faith and Science

CNS photo / Andy Clark, Reuters

News has been circulating around the Internet in the last several days that tonight’s full moon — March 19 — will make a very close approach to earth and appear bigger and brighter than it has in 18 years. Some are dubbing it the “supermoon.”

Is it true? Or it is another false claim like last summer’s eye-roller that Mars was moving in its orbit close enough to earth to appear as big as the full moon?

This time, rest assured, the news is true. But don’t expect to see anything worth dragging your family and friends outside to see.

Tonight’s moon is at perigee — the point in its orbit when it’s closest to earth. It will be about 31,000 miles closer than when it’s at the farthest point in its elliptical orbit, called apogee. It’s a fairly rare event for the full moon to coincide with perigee.

But it really won’t look much different in the sky. Compared to last month’s full moon, it will appear just 2 percent bigger in diameter, according to Sky & Telescope magazine. Compared to a full moon at apogee, it will appear about 14 percent bigger — somewhat noticeable, but still not eye-poppingly different.

And, one rumor regarding the ‘supermoon,’ is not true: Geologists say concerns that tidal forces tonight will lead to major earthquakes and other natural disasters are unfounded.

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About Joe Towalski

Editor of The Catholic Spirit, husband, dad, baseball fan(atic), astronomy buff. Follow me on Twitter @towalskij

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