How the Earth gave the Moon a lemon shape
Scientists have found that the Earth’s gravity combined with the Moon’s rotation forced the satellite to become “lemon-shaped.”
As the Moon solidified, its rotation caused it to elongate along its polar axis. But because the length of the Moon’s rotation was the same as its orbit, with one hemisphere always facing the Earth, the tidal force of the Earth’s gravity then pulled at the center, distorting the Moon’s shape so that one hemisphere bulged Earthward.
This theory is not new, but these new calculations are more robust, lending greater weight to it.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Scientists have found that the Earth’s gravity combined with the Moon’s rotation forced the satellite to become “lemon-shaped.”
As the Moon solidified, its rotation caused it to elongate along its polar axis. But because the length of the Moon’s rotation was the same as its orbit, with one hemisphere always facing the Earth, the tidal force of the Earth’s gravity then pulled at the center, distorting the Moon’s shape so that one hemisphere bulged Earthward.
This theory is not new, but these new calculations are more robust, lending greater weight to it.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
I’ve always wondered if the maria which dominate the near side of the moon were essentially caused by tidal action on the young Moon whereby the Earth’s gravity literally pulled an ocean of liquid magma up through fissures on the young thin crust. This magma would have pooled and formed the maria floors. Given the Moon was much closer to the Earth during its formation, Earth’s gravity was probably one of the dominating factors that give the Moon a number of odd characteristics.
I’ve read other theories regarding the maria that internal radioactivity that kept the Moon’s interior on the near side hotter than on the far side, but I’m don’t see a mechanism by which radioactive elements wouldn’t generally be evenly distributed within the Moon’s interior. Or other theories that the Earth somehow steered large objects to predominantly strike the near side of the moon, but this doesn’t seem to make much sense either. Finally, I’ve seen other theories that the young Earth’s surface was so hot that it heated up the near surface of the Moon and filled the maria with magma from this heat, but I don’ think the Moon was ever close enough for heat that radiated from Earth to have much impact on the moon.
Anyway, fun stuff to think about.