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Lunar Mysteries: Four Things We Still Don't Know About the Moon

The moon | NASA
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Relive the excitement of man’s first steps on the moon and the long journey it took to get there with 20 new hours of out of this world programming on KCET's “Summer of Space"  Watch out for “American Experience: Chasing the Moon” and a KCET-exclusive first look at "Blue Sky Metropolis," four one-hour episodes that examine Southern California’s role in the history of aviation and aerospace. 

The moon is many things. It's our nearest neighbor in space. It's responsible for the way the tides rise and fall. Flora and fauna respond to its patterns. The Earth rotates in the way it does because of it. 

These are not the only benefits afforded to our planet by the moon's presence, of course; the moon is integral to life as we know it. Even though it's long been studied, visited by twelve astronauts and several robots, the moon remains a source of mystery. 

It's mesmerizing to consider how much is left to learn about our orbiting companion. As we reflect on the first moon landing fifty years ago, it's also the perfect time to appreciate the mysteries left to be unlocked and to consider the future of humans on the moon. Perhaps future researchers on the moon will be able to provide answers to these looming lunar questions. 

Reimagine the space race and upend many conventional myths on “Chasing the Moon,” a film by Robert Stone.
"Chasing the Moon" Official Trailer

Where Did the Moon Come From? 

It's kind of strange to acknowledge that scientists aren't certain about the origins of the moon. There is a prevailing theory, but even that theory is problematic, which is why experts haven't declared the question of the moon's origin to be truly answered. While there is one widely accepted explanation, there are a few other theories that are interesting to consider. Notably, none involve hypotheses related to cheese.

The fission theory suggests that the moon and the Earth were once the same body that separated early on in the history of the solar system, while the capture theory posits that the moon existed elsewhere in the solar system and was trapped by the Earth's gravity, where it remains today. The condensation theory proposes that the Earth and the moon were formed at the same time from the nebula that created the whole solar system. 

The most widely accepted theory is known as the "giant impact hypothesis," which suggests that a Mars-sized object, a planetoid dubbed "Theia," crashed into the Earth about 4.5 billion years ago during the solar system's early formation. The impact sent chunks of young Earth flying into space. Those chunks of Earth were pulled back together by gravity, trapped by Earth's orbit, and eventually transformed into the moon we see today.

Artist concept of body the size of our moon slamming into a body the size of Mercury. | NASA/JPL-Caltech
Artist concept of body the size of our moon slamming into a body the size of Mercury. | NASA/JPL-Caltech

NASA notes that this impact would have been 100 million times larger than the asteroid collision that caused the dinosaurs' extinction. However, because the moon and the Earth are basically chemically the same, this theory doesn't explain why there are no traces of whatever Theia might have been made of found on the moon. Theia could have been chemically similar to the Earth, but it is unlikely, considering that Theia probably originated very, very far away.

Scientists have additional theories to explain how this happened, such as a notion proposed by scientists Kun Wang and Stein Jacobsen that suggests that when the impact occurred, both the Earth and Theia were vaporized, and their remains mixed as gasses and eventually reformed into each body. This could account for the similarities between the Earth's and the moon's compositions. However, without further proof to substantiate these theories, we cannot be entirely sure where the moon came from, which is kind of fun to think about. 

Was There Ever Life on the Moon?

Flashback to roughly 4.5 million years ago to the era when the collision between Earth and Theia took place, if that is indeed what happened. It's thought that during that volatile time, water and heat (handy to have around when creating life) abounded.

The moon was once volcanically active, and volcanic activity would have influenced its atmosphere, according to If these scenarios were the case, the moon could have actually had an atmosphere as well as oceans — the makings of a hospitable environment for life. Scientists also suggest that because the moon's habitable era was during the early formation of the solar system, when impacts were much more common, biological material from elsewhere could have hitchhiked on a celestial body that crashed into the moon, depositing life. 

The moon's volcanic history influences its modern topography. | NASA/Goddard Space Flight Center/Arizona State University
The moon's volcanic history influences its modern topography. | NASA/Goddard Space Flight Center/Arizona State University

The moon's current status as desolate and lifeless will change if humans return to it. If we set up camp on the moon, we'll bring all kinds of life there — from the obvious, our human bodies — to whatever living things we pack along with us or grow, to our many hitchhiking germs. 

What About the Moon's Magnetic Field?

Earth's magnetic field is key to protecting our planet from phenomena such as solar winds and radiation, and data points to the moon having had a strong magnetosphere, too — some billions of years ago. 

When Apollo astronauts brought back samples from the moon, scientists were surprised to discover that some of the moon rocks were magnetic. This means that, at one point, the moon had a magnetic field generated by its core. In fact, data gathered by researchers at Rutgers University revealed that it was a quite robust magnetosphere. 

By analyzing a moon rock — specifically a 1 to 2.5-billion-year-old glass-covered rock brought back by Apollo 15 astronauts in 1971 — in a magnetometer, the scientists concluded that the moon's magnetic field was once as strong as the Earth's is today. As to when the field declined and disappeared, those remain mysteries that scientists are eager to solve. 

Is There an Asteroid Buried at the Moon's South Pole? 

Could there be buried treasure on the moon? Yes, but probably not a chest of space doubloons, but rather the remnants of extra lunar objects that once crashed into the moon — a treasure trove of precious information about the solar system's formative years. 

Data from two NASA programs, the Lunar Reconnaissance Orbiter (LRO), which is still studying the moon, as well as the two satellites that were part of the Gravity Recovery and Interior Laboratory (GRAIL), revealed some interesting data. The sets of data pointed toward something strange going on at the Moon's South Pole-Aitken basin. The South Pole-Aitken basin is the largest known impact basin on the moon, with a diameter of approximately 1,500 miles. 

When scientists compared data from LRO and GRAIL, they observed that the topographical features did not line up with the "gravitational tug" of the location. Scientists theorize that the source of the increased gravitational pull is the same as the source of the crater: an asteroid. 

The South Pole-Aitken basin, shown in blue. | NASA/Goddard Space Flight Center/University of Arizona
The South Pole-Aitken basin, shown in blue. | NASA/Goddard Space Flight Center/University of Arizona

When the dense asteroid impacted the moon, it created the crater and is now buried below it. Another theory about the anomaly is that it's the result of a magma ocean cooling and solidifying. Perhaps with further study of the South Pole-Aitken basin, we will have our answer. Crater, former magma ocean, or other? Time and science may tell. 

Other Mysteries? 

These are not, of course, the only mysteries of our moon. The more scientists discover, the more questions arise. As we send human explorers and more advanced robots to the moon as part of the Artemis Moon Program or on commercial space exploration efforts, we will be able to go farther, dig deeper and look closer at our nearest neighbor. We will surely get to the bottom of some of these mysteries and learn which new questions to ask about the moon.

After all, when Apollo astronauts brought back samples and rocks, our understanding of the moon changed. What will happen when future astronauts get their hands of more kinds of samples? Well, we will be over the moon to find out.

For now, the moon, the lovely lunar bag of tricks that it is, will keep tides ebbing and flowing, stargazers gazing and scientists theorizing. 

Top Image: The moon | NASA

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