NASA solar probe snaps elusive asteroid trails for the first time

A "catastrophic" event that shattered asteroid 3200 Phaethon left a dusty tail of debris. Astronomers have finally seen it.

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Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, he realized, was the best job in the world -- it let him tell stories about space, the planet, climate change and the people working at the frontiers of human knowledge. He also owns a lot of ugly Christmas sweaters.
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Parker Solar Probe's WISPR camera suite captured the elusive dust trail, pictured here (dotted line).

Brendan Gallagher/Guillermo Stenborg

The Parker Solar Probe, one of NASA's most extreme spacecraft, has been gathering data on our sun for the past year, revealing some unusual phenomena in the outer atmosphere. But solar science isn't the only feather in PSP's extremely hot hat. Astronomers at the US Naval Research Laboratory (NRL) have used the probe's specialized camera to detect the faint signal of an asteroid dust trail that has avoided detection for decades. 

Parker is equipped with the Wide-Field Imager for Solar Probe (WISPR), a suite of cameras built specifically for taking photos around the sun. Usually, light from the trail is obscured by the brightness of the sun, but the WISPR cameras are specially designed to filter out all that light, giving astronomers a chance to see the faint dust cloud trailing asteroid 3200 Phaethon.

Phaethon is a well-characterized and slightly bizarre asteroid, about 3.6 miles in width, that more closely resembles a comet. It travels closer to the sun than any other named asteroid but its trail is particularly visible near the star, because it's more densely packed. It also has a dark past.

"Something catastrophic happened to Phaethon a couple of thousand years ago and created the Geminid Meteor shower," said Karl Battams, a computational scientists at the NRL's space science division, in a statement

Watch this: NASA's Parker Probe: Everything you need to know about the plan to 'touch the sun'

That catastrophic event caused Phaethon to spill debris all over its orbit and, each year, pieces of the rock cause the Geminids meteor shower, one of the brightest visible from the Earth. The researchers believe the dust they are seeing in WISPR images is part of this phenomenon. 

"There's no way the asteroid is anywhere near active enough when it is near the sun to produce the mass of dust we are seeing, so we are confident that WISPR is seeing part of the Geminid meteor stream," said Battams.

The Japanese Space Agency plans to fly a spacecraft called Destiny+ to the asteroid in 2022. The spacecraft will analyze the dust generated by Phaethon and visit other small bodies in the solar system, hoping to better characterize the types of debris they're spewing.

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