Monday, October 26, 2015

The Distance Between Earth And Moon Is Only 48 Round Trips From D.C. To San Francisco

Composite image of the Moon as taken by the Galileo spacecraft on 7 December 1992. The color is "enhanced" in the sense that the CCD camera is sensitive to near infrared wavelengths of light beyond human vision.

"Ten Things You Don't Know About The Moon
Time Magazine

Thing #2:
"While our two celestial bodies remain locked in orbit, the moon is slowly — very slowly — inching away from Earth, at a rate of about 3.8 cm a year. Right now the moon is more than 238,000 miles from Earth, but when it formed, it was just 14,000 miles away.
How do scientists know? The moon's distance is measured by bouncing laser beams off reflectors on the moon's surface that astronauts from the Apollo missions left behind. Scientists can measure the time it takes for the laser beams to travel there and back and calculate the distance with a high degree of accuracy. Eventually, the moon's distance will substantially weaken the oceans' tides and total eclipses of the sun won't be possible for observers on Earth, since the moon will have moved too far away. But that could still take another billion years."
The Dark Side

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