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Mystery Moon Swirls Caused by Blasts of Comet Gas?

Strange bright swirls have long been known to exist on the moon's surface and their origin is steeped in mystery -- might comets be the culprit?

Strange bright swirls have long been known to exist on the moon's surface and their origin is steeped in mystery. Often stretching thousands of miles across the lunar landscape, scientists have tried to make connections with the elegant curved shapes with the moon's interior magnetism or interactions between moon dirt and the solar wind, but these explanations have fallen short.

Now, inspired by the Apollo moon landings and armed with a powerful computer model, researchers at Brown University think they have an alternative answer for these swirly patterns.

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Over the past 100 million years, many small comets impacted the moon's pockmarked surface. Along with the icy nuclei that carved craters into the moon rock, the gaseous comet atmospheres - known as a comet's coma - would have also blasted into the moon's uppermost layer of regolith, possibly leaving the swirly imprint.

"We think this makes a pretty strong case that the swirls represent remnants of cometary collisions," said planetary geoscientist Peter Schultz, at Brown University.

Like a strong gust of wind blowing across a dry, dusty beach, Schultz and co-investigator Megan Bruck-Syal (who is now a researcher at the Lawrence Livermore National Laboratory) believe that as a comet hits the moon's surface, the coma also blasts into the surface, blowing away the dark, lightweight upper layers of regolith (the moon's fine dusty "soil"), exposing the brighter layers below.

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This hypothesis takes its lead from the Apollo lunar modules that landed on the moon in the 1969′s and 70′s.

"You could see that the whole area around the lunar modules was smooth and bright because of the gas from the engines scoured the surface," said Schultz in a Brown press release. "That was part of what got me started thinking comet impacts could cause the swirls." These findings have been published in the journal Nature.

Through the use of computer simulations, Schultz and Bruck-Syal have revealed that the impact of comets on the moon could indeed create the vast swirls - the eddies and vorticies created by the gaseous coma impacting the lunar surface appear to leave their own special kind of imprint in the uppermost layers of regolith, often far from the parent comet's impact crater.

These simulations may also explain the magnetic anomalies discovered near the swirls. During a comet impact on the moon, small iron-rich particles would melt and cool and align in the direction of the magnetic field carried by the comet.

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"Comets carry with them a magnetic field created by streaming charged particles that interact with the solar wind," Schultz said. "As the gas collides with the lunar surface, the cometary magnetic field becomes amplified and recorded in the small particles when they cool."

These are some of the most sophisticated computer simulations of the origin of the mysterious swirls and they certainly provide a compelling explanation, but further observational evidence is needed.

"Everything we see in simulations of comet impacts is consistent with the swirls as we see them on the moon. We think this process provides a consistent explanation, but may need new moon missions to finally resolve the debate."

Source: Brown University via Phys.org

This NASA Lunar Reconnaissance Orbiter observation shows the vast swirls of Reiner Gamma in the Oceanus Procellarum region of the moon, to the west of the crater Reiner. Scientists have long pondered the origin of these swirl patters and others like them and new computer simulations point to cometary impacts being a possible cause.

On July 16, 1969, Commander Neil Armstrong, Lunar Module Pilot Buzz Aldrin and Command Module Pilot Michael Collins launched atop a Saturn V rocket toward the moon. The 8-day NASA mission captivated the planet as Armstrong and Aldrin explored the lunar surface on July 20, supported by Michael Collins who orbited overhead. 46 years after the first successful landing of the Apollo program, we've dug into the NASA archives to find some familiar and some not-so-familiar views of the Apollo 11 mission. All photos and captions can be found in

NASA's Human Spaceflight Gallery

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Neil Armstrong leads the way across Pad A, Launch Complex 39 at Kennedy Space Center, Fla., during the Apollo 11 prelaunch countdown on July 16, 1969. Michael Collins follows behind.

The massive 363-feet tall Apollo 11 launched at 9:32 a.m. (EDT) on July 16, 1969, carrying Armstrong, Aldrin and Collins into the history books.

This photo was taken from a door-mounted camera on a U.S. Air Force EC-135N aircraft shortly after launch. The Saturn V second and third stages separate from the spent first (S-1C) stage, which then dropped into the Atlantic Ocean. Recently, the first stage engines were retrieved from the ocean floor by Amazon.com founder Jeff Bezos.

Earth is captured through the Apollo astronauts' camera lens on the way to the moon.

Earth shrinks as Apollo 11 continues its journey.

Aldrin looks into the TV camera during the third broadcast from space on the way to the moon.

The Apollo 11 Command and Service Modules (CSM) are photographed from the Lunar Module (LM) in lunar orbit during the Apollo 11 lunar landing mission.

After descending from the lunar module after a successful landing on July 20, 1969, Armstrong makes a bootprint in the loose lunar regolith. The astronauts' bootprints remain untouched on the dusty surface to this day.

Aldrin descends the steps of the Lunar Module ladder as he prepares to walk on the moon.

Armstrong and Aldrin deploy the American flag outside the lunar module "Eagle" at Tranquility Base in the Sea of Tranquility on July 20, 1969.

Aldrin prepares to deploy experiments on the lunar surface next to the large lunar module, "Eagle."

Aldrin oversees the deployment of the Early Apollo Scientific Experiments Package (EASEP), photographed by Armstrong during the crew extravehicular activity (EVA).

Aldrin stands next to one of the lunar module legs.

Armstrong inside the lunar module just after his famous moonwalk.

Collins photographs the returning lunar module with Armstrong and Aldrin inside. Soon after, the lunar module docked with the orbiting Command and Services Modules to begin the journey back to Earth.

Aldrin illustrates the gyroscope principle under zero-gravity conditions using a can of food in front of the TV cameras as the crew travel back to Earth from the moon.

The three Apollo 11 crew men await pickup by a helicopter from the USS Hornet, prime recovery ship for the lunar landing mission, after a fiery reentry and splashdown in the Pacific Ocean.

Mission Operations Control Room in the Mission Control Center, Building 30, Manned Spacecraft Center (MSC), showing the flight controllers celebrating the successful conclusion of the Apollo 11 lunar landing mission.

The Apollo 11 spacecraft Command Module and the Mobile Quarantine Facility are photographed aboard the USS Hornet.

Left to right: Armstrong, Aldrin and Collins, in a 21-day quarantine, are greeted by their wives.

New York City welcomes Apollo 11 crewmen in a showering of ticker tape down Broadway and Park Avenue in a parade termed as the largest in the city's history on Aug. 13, 1969.