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Moon’s bulge reveals its slow retreat from Earth

13 Feb 2018, 11:07 UTC
Moon’s bulge reveals its slow retreat from Earth University of Colorado Boulder
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Full moon from UC Boulder.
Reflectors placed on the moon during manned moon missions have let earthly astronomers accurately measure the moon’s distance. That’s how we know that – today – the moon’s distance from Earth is increasing at a rate of about about 1.6 inches (4 cm) per year. What we haven’t known with any accuracy is how fast the moon was retreating long ago. Now researchers have announced results of new dynamic model – a computer simulation over time – based on the current size of the moon’s equatorial bulge. The model sets parameters on how fast or slowly the moon was receding from Earth, billions of years ago. It has implications for what the Earth, moon and other solar system bodies were like early in the history of our solar system.
The study was published online on February 2, 2018 in the American Geophysical Union’s peer-reviewed journal Geophysical Research Letters. Theoretical geophysicist Chuan Qin, formerly of University of Colorado, Boulder (UC Boulder), now at Harvard, led the study.
The Earth and other planets in our solar system are thought to have formed from a cloud of dust and gas orbiting the young sun, four-and-a-half billion years ...

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