Support for the Giant Impact Hypothesis of Moon Formation
The origins of the Moon have been as murky as a black hole’s interior, but now a new study shines light on the Moon’s making. Scientists aren’t completely sure how the Moon formed but they have a prevailing theory, the Giant Impact Hypothesis, which suggests that the Moon was formed by a collision between a proto-Earth and a solid object of mysterious composition called Theia.
Read more about this research from the 6 June issue of Sciencehere.
The first spacecraft to orbit the moon detected a stronger pull of gravity when it passed over ancient basins, once filled by thick lava flows, called mare basalts. These areas, in which mass is intensely concentrated, became known as “mascons,” and a new study by H. Melosh and colleagues explains their formation as well as their unique, bulls-eye-shaped gravity signatures.
Read more about this research from the 30 May issue of Science Express here and here.
[Image courtesy of H.J. Melosh, Purdue University and the NASA GRAIL team. Click the image for more information.]
43 years ago today, in 1969, the Apollo 11 spacecraft touched down on the moon. Across the world, people watched as astronaut Neil Armstrong became the first man to walk on the moon, followed shortly by Buzz Aldrin. According to NASA, the pair spent 21 hours on the moon and brought back a total of 46 pounds of moon rocks. And of course, Armstrong was engraved in history for his now famous quote, “That’s one small step for a man, one giant leap for mankind.”
This cover of the September 17, 2010 issue of Science shows a topographic map of the Moon based on measurements from the Lunar Orbiter Laser Altimeter. Image: NASA/LRO/LOLA/GSFC/MIT/Brown. Click the image for more information.
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Researchers have identified fragments of meteorites that hit the Moon in the ancient past. It’s been unclear whether the objects bombarding Earth and the Moon early in the Solar System’s history were primarily asteroids, comets, or an even mixture of both. The new study describes small meteorite fragments preserved in ancient lunar rocks from the Apollo 16 landing site. The results suggest that asteroids were probably the more common type of impactor.
Read more about this research from the 10 May issue of Science Express here.
Ancient Impact May Explain the Moon’s Magnetic Quirks
A giant asteroid that struck the Moon long ago, creating the largest impact crater in the solar system, could explain the surprisingly strong magnetic fields that emanate from the lunar crust, researchers say. These magnetic anomalies on the Moon were first discovered by the Apollo missions back in the 1960’s, but scientists have been hard-pressed to explain them since. Now, Mark Wieczorek of Université Paris Diderot and colleagues have performed detailed computer simulations of major lunar impact events, like the one that created the oldest and largest crater in the solar system, known as South Pole-Aitken basin.
Read more about this research from the 9 March issue of Sciencehere.
A convecting dynamo of molten metal, akin to the one within Earth, likely churned within the Moon’s core for much longer than previously thought, new research suggests. The Moon’s magnetic field would also have been much stronger during that time, as a result. These findings challenge current theory and imply that researchers will need to find alternative power sources that could have generated such a long-lived dynamo.
Read more about this research from the 27 January issue of Sciencehere.