Basking in the Warmth of the Full Moon

The full moon may give northerners more benefits than just a savings on headlamp batteries.

In a study recently published in Geophysical Research Letters, three Arizona State University scientists claim the earth's poles are warmer during the full moon. Polar regions are .55 degrees Celsius warmer during full moon when compared to the temperature during new moon, the scientists found.

Less than a degree Celsius of warmth isn't enough to make you strip off your parka, but the researchers found it intriguing that the warmth was felt at the earth's poles while tropical temperatures showed no relationship with the full moon.

We see a full moon once every 29 days, 12 hours and 44 minutes, when the moon orbits the earth to a position where we see the moon's sunlit side. The full moon rises in the east as the sun sets to the west, traveling all night across the sky until the sun rises the next day.

The new moon rises and sets with the sun, which blinds us to the new moon's presence. The moon waxes (appears to grow larger) following the new moon, rising about 50 minutes later each day. By the first quarter of the 29-day lunar cycle, this lag in rising makes the moon appear directly overhead when the sun is setting. At first quarter we see the moon half illuminated, with a straight-line boundary between dark and light.

From the half moon of first quarter, the moon continues waxing into a pregnant, gibbous moon (from the Latin word for "bulging"), as it nears the midpoint of the lunar cycle, full moon.

Arizona State University graduate student John Shaffer analyzed 17 years of satellite temperature data to calculate the apparent pole-warming ability of the full moon. Satellites are able to measure the motion of oxygen molecules from the ground surface to about four miles up, and then translate that motion into a temperature reading, Shaffer said.

How could the moon excite the poles' air molecules? At the closest point in its egg-shaped orbit around the earth, the moon is 221,463 miles away. Even though its sunlit surface is hotter than boiling water, that's a long way for heat to travel. It's too far for us to feel the warmth of moon rocks, Shaffer said.

"The actual radiation from the moon is not significant enough to effect temperatures (on Earth)," Shaffer said. The moon also isn't a very good mirror. The moon's surface absorbs most of the sun's energy that hits it, reflecting only about six percent of the sun's radiation, Shaffer said.

Sue Ann Bowling, an assistant professor of geophysics at the Geophysical Institute, pulled out her calculator and figured that the warmth of the full moon is comparable to that of the sun when the sun is just barely above the horizon. As Alaskans know, a low sun doesn't warm us enough to even tingle our noses.

The moon may affect Earth's temperature in other ways than radiating heat or reflecting sunlight, Shaffer said. Other researchers have speculated that just as the moon's gravity causes the tides by pulling the oceans upward, the moon may push and pull on the atmosphere, the 30-mile shell of gases that surrounds Earth. An atmosphere manipulated like Silly Putty could change the global position of the jet streams and other weather phenomena, Shaffer said. The moon could effectively push storm systems to other areas of the globe.

As Shaffer pointed out, his study is no reason to leave your mittens home when the moon is full. But the moon might need to be included when scientists look at what affects the earth's weather.