© Rensselaer Polytechnic InstituteMicrotektites as first seen in a sediment sample from the onset of the Paeocene-Eocene Thermal Maximum.
A comet strike may have triggered the Paleocene-Eocene Thermal Maximum (PETM), a rapid warming of the Earth caused by an accumulation of atmospheric carbon dioxide 56 million years ago, which offers analogs to global warming today. Sorting through samples of sediment from the time period, researchers at
Rensselaer Polytechnic Institute discovered evidence of the strike in the form of microtektites - tiny dark glassy spheres typically formed by extraterrestrial impacts. The research will be published tomorrow in the journal
Science.
"This tells us that there was an extraterrestrial impact at the time this sediment was deposited - a space rock hit the planet," said
Morgan Schaller, an assistant professor of earth and environmental sciences at Rensselaer, and corresponding author of the paper.
"The coincidence of an impact with a major climate change is nothing short of remarkable." Schaller is joined in the research by Rensselaer professor Miriam Katz and graduate student Megan Fung, James Wright of Rutgers University, and Dennis Kent of Columbia University.
Schaller was searching for fossilized remains of Foraminifera, a tiny organism that produces a shell, when he first noticed a microtektite in the sediment he was examining. Although it is common for researchers to search for fossilized remains in PETM sediments, microtektites have not been previously detected. Schaller and his team theorize this is because microtektites are typically dark in color, and do not stand out on the black sorting tray researchers use to search for light-colored fossilized remains. Once Schaller noticed the first microtektite, the researchers switched to a white sorting tray, and began to find more.
At peak abundance, the research team found as many as three microtektites per gram of sediment examined. Microtektites are typically spherical, or tear-drop shaped, and are formed by an impact powerful enough to melt and vaporize the target area, casting molten ejecta into the atmosphere. Some microtektites from the samples contained "shocked quartz," definitive evidence of their impact origin, and exhibited microcraters or were sintered together, evidence of the speed at which they were traveling as they solidified and hit the ground.
Comment: The American Meteor Society (AMS) received over 600 reports about a fireball seen over MS, GA, TN, LA, FL, AL, KY and TX on Wednesday, October 12th 2016 around 11:48 UT.
According to Mike Hankey of the AMS "This was rarer than most as it was seen early in the morning. Also several reports of big smoke cloud left behind."
The object was was first seen 65 miles above Sawyersville, Alabama and moved west at about 89,000 mile per hour. NASA said "It appears to have fragmented 41 miles above Louisville, Mississippi."