Wednesday, April 26, 2023

NASA thought it knew source of annual Geminid meteor shower. Turns out, it was wrong

2023/04/25
A meteor streaks through the night sky over Myanmar during the Geminid meteor shower seen from Wundwin township near Mandalay city on Dec. 14, 2018
- Ye Aung Thu/GETTY IMAGES NORTH AMERICA/TNS

NASA just admitted a big scientific “oopsie” — and the ripple effect has left experts scratching their heads over Earth’s annual Geminid meteor shower.

The mistake involves the tail of Phaethon, an asteroid long assumed to be the source of meteors showering Earth each December.

Closer analysis of Phaethon by a team of scientists revealed its tail isn’t dusty at all.

Instead, it’s sodium gas, NASA revealed in a Tuesday news release.

So if the tail of the asteroid is gas, not dust, where are the dazzling Geminid meteors coming from?

Scientists aren’t sure. The only thing NASA knows for sure is “a weird asteroid has just gotten a little weirder.”

“We have known for a while that asteroid 3200 Phaethon acts like a comet. It brightens and forms a tail when it’s near the Sun, and it is the source of the annual Geminid meteor shower,” NASA reported. “Scientists had blamed Phaethon’s comet-like behavior on dust escaping from the asteroid as it’s scorched by the Sun.“

Phaethon was discovered in 1983, and scientists quickly realized its orbit “matched” the Geminid meteor shower. They concluded its debris trail must be behind “a swarm of shooting stars.” This year, the shower is expected to arrive Nov. 19 and continue through Christmas Eve, according to EarthSky.org.

The team of scientists who made the discovery — including California Institute of Technology PhD student Qicheng Zhang — have a vague theory about the origin of the spectacle.

It’s possible the annual light show is the result of a “disruptive event” tied to the asteroid that dates back thousands of years, the team says.

“Perhaps a piece of the asteroid breaking apart under the stresses of Phaethon’s rotation ... caused Phaethon to eject the billion tons of material estimated to make up the Geminid debris stream,” the team said. ”But what that event was remains a mystery.”

A DESTINY+ spacecraft is scheduled to fly past Phaethon later this decade, possibly providing answers while taking images of the surface, NASA says.

Phaethon is considered an “enigmatic asteroid” for many reasons, including the fact asteroids aren’t known for having comet tails, experts say.

Asteroids are mostly rock, while comets are a combination of ice and rock. It’s that mix of elements that “form tails as the Sun vaporizes their ice, blasting material off their surfaces and leaving a trail along their orbits,” NASA says.

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© The Charlotte Observer

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