Moon Shadow Makes Atmospheric Waves
Next time Cat Stevens is being followed by a moon shadow, maybe he should try surfing.
As the Moon blots out the Sun during a solar eclipse, the patch of the Earth that is cast into darkness cools. Meanwhile, the surrounding regions continue to receive the full brunt of the Sun's energy.
This temperature difference causes waves in the atmosphere to build up behind the leading edge of the moon's shadow, like the bow wave of a ship.
Although scientists have hypothesized about the moon's atmospheric wake since the 1970's, it wasn't until a July 22, 2009 eclipse in Japan and Taiwan that they observed the phenomenon directly.
The waves came from both the leading and trailing edges of the Moon's shadow and traveled about 100 meters (328 feet) per second.
If the Moon were a real ship, it would make the Titanic look like a dinghy. There was a 30 minute difference between the leading and trailing waves. That means that the Moon's shadow would be a ship approximately 1,712 kilometers (1,064 miles) long.
The research was published in Geophysical Research Letters. J. Y. Liu of the National Central University of Taiwan led the research.
This image from the Japanese geostationary satellite MTSAT shows the view of Earth at 9:30 a.m. local time in Taiwan, near the time in eastern China when the disk of the Moon completely overlapped the disk of the Sun. (Wikimedia Commons)
The 2009 eclipse as seen in Kikiaijima, Kagoshima, Japan (Wikimedia Commons)
The path of the July 22, 2009 solar eclipse, the bold blue line in the center is where the eclipse was total. (Wikimedia Commons)