Mystery Fireball That Lit Up Sky And Baffled Scientists Finally Explained

 

Despite originating from a remote region of the Solar System where comets are supposed to originate, scientists have determined that a strange space rock that lit up the skies across parts of Canada in February 2021 wasn't a comet.

The space rock, which created an extremely bright light and luminous trail that lasted for several seconds after it plowed into Earth's atmosphere at 38.5 miles per second, was noticed in Canada's Alberta region soon before dawn on February 22 of last year.

Based on several studies, scientists determined that the object had been orbiting the sun for almost 1,000 years before it struck Earth, which indicates that it must have come from a very far-off region of the Solar System known as the Oort Cloud.

This caused a difficulty. The Oort Cloud is a dense shell made up of billions or maybe trillions of ice objects that orbit the sun at distances much further than Pluto's orbit. Some of these objects occasionally are thrown out of the Oort Cloud and land in the inner Solar System, where they turn into comets, which are enormous ice and dust particles that leave distinctive trails as they go closer to the sun.

In general, experts have assumed that the Oort Cloud is made up of such things. The item that exploded over Alberta, though, didn't resemble a comet. It appeared more like a meteoroid, which are rock or iron lumps that resemble asteroids but are smaller and are more likely to remain in the inner solar system.

Our understanding of how the Oort Cloud formed may be altered by the discovery of stony meteoroids there.

According to Karen Meech, an astronomer at the University of Hawaii Institute for Astronomy, "the Oort Cloud was populated by planetesimals—small objects that accumulated to grow into planets—that were gravitationally scattered by the giant planets, primarily Jupiter and Saturn, as the solar system was forming." "It was long believed that the Oort cloud was filled by comets because the massive planets originated in a region of the solar system where it was cold and there was a lot of icy material accessible."

A number of comets from the Oort Cloud that don't act as they should have have been found by Meech and her colleagues. One reason is that comets should start to become active as they travel closer to the sun and begin to leave tails of gas and dust behind them. The term "Manx comets" refers to a breed of tailless cat, and some of them haven't been acting in this way.

Particularly one of these Manx comets didn't emit the typical tint of light for comets. In order to determine what materials comets are made of, scientists examine their light.

One of the Manxes, according to Meech, "had an absorption at the far end of the visible spectrum right before the near infrared at 1 micron, not this type of chemical signature." This absorption is typical of minerals found in stony asteroids in the inner solar system.

What this means for our views of how the solar system developed was explained to Newsweek by Bill Bottke, director of the Department of Space Studies at the Southwest Research Institute.

It could indicate that the early asteroid belt was more massive, allowing for a greater proportion of the Oort cloud to be made up of debris expelled from it during early planet formation processes.

According to Alan Jackson, a planetary astronomer at Arizona State University, Tempe, the discovery of Oort Cloud non-comets like the Alberta one could support the Grand Tack hypothesis, which contends that in the early Solar System, Jupiter once traveled as close to the sun as Earth, sweeping up many rocky objects and flinging them out toward the Oort Cloud.

For the time being, it is hoped that stranger fireballs, like the one that occurred in Alberta in 2021, will help to clarify these possibilities.

Denis Vida, a meteor scientist at Western University, presented research on the 2021 Alberta fireball at the 54th annual Division for Planetary Sciences of the American Astronomical Society meeting, which this year was held in London, Ontario, between October 2 and October 7.

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