Photo courtesy of Robert Traverso
Before NASA successfully landed humans on the moon for the first time in history, very little was known about the moon’s origin.
In a lecture titled, “How the Apollo Program Solved the Riddle of the Origin of the Moon,” J. Bret Bennington, chair of the department of geology, environment and sustainability at Hofstra, along with Stephen Lawrence, a professor in the department of physics and astronomy, shared insight on the origin of the moon to a packed audience at the Cradle of Aviation Museum and Education Center in Garden City, New York.
The eventtook place on Wednesday, Nov. 28, inside the museum’s planetarium as part of Hofstra’s annual public lecture series, “Science Night Live,”
The leading pre-Apollo view, known as the co-accretion theory, argued that the Earth and moon formed at the same time. The Apollo program changed our understanding of the origin of Earth’s moon, debunking the co-accretion theory and every other moon formation hypothesis of that era.
Bennington explained that not only did NASA manage to map the entirety of the moon’s orbit, but it also successfully placed geophysical instruments on the lunar surface that provided us with previously unattainable data. Most importantly, Apollo astronauts obtained moon rocks that have since been studied on Earth.
“Samples collected by Apollo astronauts established radiometric ages for major lunar features, revealing the timeline of the geological evolution of the Earth,” read one slide from the duo’s PowerPoint presentation, which was projected onto the planetarium dome.
Bennington, who has taught at Hofstra since 1993, spoke in depth about the geology of the moon and what it has revealed about its origin.
Bennington explained that Uranium-lead dating of the Apollo moon rocks allowed scientists to produce a timeline of the moon’s evolution in space for the first time.
“The moon formed within 500 million years or so after the Earth formed,” Bennington said. “[The moon] didn’t form at the same time as Earth.”
Following the Apollo program’s findings, the giant-impact hypothesis was put forth by several scientists during the mid-1970s.
“[The giant-impact theory is] the best theory we can dream up that doesn’t contradict the [Apollo] data,” Lawrence said. “[The moon] formed from super-hot debris ejected when a large protoplanet struck early Earth.”
Named Theia after the mother of the moon goddess in Greek mythology, the large protoplanet, estimated to have been about the size of Mars, was destroyed upon impact with Earth. Theia then dissipated into a large disk of gas, which merged over time into what we recognize today as the Earth’s moon.
Amelia Willard, a sophomore sociology major, said that prior to the lecture she had never considered that information regarding the composition of the moon and the Earth could help with “figuring out the origin of the moon.”
“Due to the evidence shown in this lecture, it is most probable that the giant-impact hypothesis is the correct view of the moon’s formation,” said Jacob Mamiye, a senior sustainability and geology major.
Despite the findings presented Wednesday night, Bennington added that scientists still have a long way to go. “It still seems likely the moon formed from a big collision, a ‘big splat’ or a ‘big whack’ or whatever you want to call it,” Bennington said. “But we’re still trying to figure out exactly how that happened.”
