UCLA-led research reconstructs massive crash, which took place 4.5 billion years ago
[img3="The extremely similar chemical composition of rocks on the Earth and moon helped scientists determine that a head-on collision, not a glancing blow, took place between Earth and Theia. (Copyright: William K. Hartmann)"]http://cms.ipressroom.com.s3.amazonaws. ... 37-prv.jpg[/img3][hr][/hr]
The Moon was formed by a violent, head-on collision between the early Earth and a “planetary embryo” called Theia approximately 100 million years after the Earth formed, UCLA geochemists and colleagues report.
Scientists had already known about this high-speed crash, which occurred almost 4.5 billion years ago, but many thought the Earth collided with Theia (pronounced THAY-eh) at an angle of 45 degrees or more -- a powerful side-swipe (simulated in a 2012 YouTube video). New evidence reported Jan. 29 in the journal Science substantially strengthens the case for a head-on assault.
The researchers analyzed seven rocks brought to the Earth from the Moon by the Apollo 12, 15 and 17 missions, as well as six volcanic rocks from the Earth’s mantle -- five from Hawaii and one from Arizona.
The key to reconstructing the giant impact was a chemical signature revealed in the rocks’ oxygen atoms. (Oxygen makes up 90 percent of rocks’ volume and 50 percent of their weight.) More than 99.9 percent of Earth’s oxygen is O-16, so called because each atom contains eight protons and eight neutrons. But there also are small quantities of heavier oxygen isotopes: O-17, which have one extra neutron, and O-18, which have two extra neutrons. Earth, Mars and other planetary bodies in our solar system each has a unique ratio of O-17 to O-16 -- each one a distinctive “fingerprint.” ...
Oxygen isotopic evidence for vigorous mixing during the Moon-forming giant impact - Edward D. Young et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
Most interesting. It is gratifying that this fascinating hypothesis is now close to becoming a widely accepted theory. (And in science-speak, a widely accepted theory is damn close to being "the truth".)
Ron-Astro Pharmacist wrote:
Theia? Why didn't it get named Thera?
We don't live on Eaith! Enough to make one Moan
https://en.wikipedia.org/wiki/Ancient_Thera wrote:
<<Ancient Thera (Greek: Αρχαία Θήρα) is an antique city on a ridge of the steep, 360 m high Messavouno mountain on the Greek island of Santorini. It was named after the mythical ruler of the island, Theras, and was inhabited from the 9th century BC until 726 AD.>>
https://en.wikipedia.org/wiki/Theia wrote:
<<In Greek mythology, Theia ("goddess" or "divine"), is a Titaness. Once paired in later myths with her Titan brother Hyperion as her husband, "mild-eyed Euryphaessa, the far-shining one" of the Homeric Hymn to Helios, was said to be the mother of Helios (the Sun), Selene (the Moon), and Eos (the Dawn).
Hesiod's Theogony gives her an equally primal origin, a daughter of Gaia (Earth) and Uranus (Sky). Robert Graves also relates that later Theia is referred to as the cow-eyed Euryphaessa ("wide-shining") who gave birth to Helios in myths dating to Classical Antiquity.
Pindar praises Theia in his Fifth Isthmian ode [say that 5 times fast - ACN]:
Mother of the Sun, Theia of many names, for your sake men honor gold as more powerful than anything else; and through the value you bestow on them, o queen, ships contending on the sea and yoked teams of horses in swift-whirling contests become marvels.
She seems here a goddess of glittering in particular and of glory in general, but Pindar's allusion to her as "Theia of many names" is telling, since it suggests assimilation, referring not only to similar mother-of-the-sun goddesses such as Phoebe and Leto, but perhaps also to more universalizing mother-figures such as Rhea and Cybele.>>
neufer wrote:
Pindar praises Theia in his Fifth Isthmian ode [say that 5 times fast - ACN]:
Thanks Art. Now I'll be able to sleep tonight. After assimilating that Fifth Isthmian Ode I might tackle Hesiod's Theogony - "to organize a narrative to tell how they came to be and how they established permanent control over the Cosmos." That sounds worthwhile.
The statement:
"Theogonies are a part of Greek mythology which embodies the desire to articulate reality as a whole; this universalizing impulse was fundamental for the first later projects of speculative theorizing."
makes me think that I've found some distant relatives.
After assimilating that Fifth Isthmian Ode I might tackle Hesiod's 
