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Sierra Daily

02/17/2011

By the Light of the Full Moon

Porchlight and Moon niemisensa

A porchlight mimics the moon in Lapland. Credit: Sami Nieminen

The date of the full moon and the evenings surrounding it have never been considered good times to stargaze. Fainter objects are washed out by the brilliant glow of the moon, and even looking at the moon itself provides only a flat view, without the terminator to bring out the sharp edges of the lunar topography.

Yet, there are still interesting things to consider when gazing at the eye-catching full moon as it crests above the horizon. Every full moon has been given a multitude of nicknames by Native Americans, Chinese, colonial settlers, and so forth. This month, the full moon occurs at 12:36 a.m. PST on Friday, February 18. February’s Full Moon is sometimes called the Snow Moon. When a full moon’s glow is reflected off the snow, the evening can be bright enough for an evening stroll. (If only it weren’t so cold out.)

If you have clear skies and can see the moon over the weekend, here are a couple things to consider. On February 19, the moon will be in perigee, lying 222,604 miles from Earth, its fifth closest of the year. (Next month the full moon and the closest moon occur on the same day.) As you gaze upward, try to get a feel for the size of this orb suspended in space. It can be tricky when there is nothing tangible to compare it to, so consider this: The moon has a diameter of about 2,160 miles. The continent of Australia is nearly the same distance across. (From Perth on the west coast to Sydney on the east coast is a span of 2,045 miles.) So as you look up at the full moon, imagine Australia stretching across the face of it to give you an idea of its size.

Now, what do you imagine it would feel like to be up there on the moon? If you’re standing outside on a chilly February night, gazing into the darkness, it’s easy to believe that the air up there would feel very frosty. But it’s a bit of a trick question, because there is no atmosphere on the moon. However, there is still a surface temperature. If you were standing on the surface during full moon and bathed in all the sun’s light, it would be 253 degrees Fahrenheit. Which, I think it’s fair to say, is hotter than it looks. If you were standing on the opposite side of the moon at this time, far from the sun’s rays in the darkness, the temperature would only be -243 degrees Fahrenheit. Which makes standing outside in February and gazing at the Snow Moon seem not such a chilly undertaking after all.

-- Kelly Kizer Whitt loves clean, clear, and dark skies. Kelly studied English and Astronomy at the University of Wisconsin-Madison and worked for Astronomy magazine. She is currently the Feature Writer for Astronomy and Space at Suite101.com. You can follow her on Twitter at twitter.com/Astronomommy.

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