First, a few years ago, NASA's Parker Solar Probe captured the first image of Phaethon's debris stream. Then it snapped a second, closer view in September 2022, as seen above. Analysis of these images confirmed what scientists had been speculating about for some time that there is so much material in the stream, there's no way the rock comet's tiny tail could account for it all.

Now, new images of the asteroid revealed something even more interesting. 3200 Phaethon's tail doesn't actually contain any dust at all. Instead, it's composed of sodium gas.

This extreme closeup of 3200 Phaethon was captured by one of NASA's STEREO spacecraft in 2010. The rock comet's short tail extends toward the bottom left of the image. Credit: Science@NASA

"Our analysis shows that Phaethon's comet-like activity cannot be explained by any kind of dust," Qicheng Zhang, a Ph.D. student at Caltech, told NASA.

Zhang is the lead author of a new study in the Planetary Science Journal that details these findings. He and his colleagues gathered images of 3200 Phaethon taken by the coronagraph instruments on board SOHO and another NASA spacecraft, the Solar Terrestrial Relations Observatory (STEREO), between 1997 and 2022.

Coronagraphs work by blocking direct sunlight from entering the camera using a small disk. As a result, the instrument can image the fainter activity around the Sun, such as coronal streamers and coronal mass ejections. The instruments also pick up any objects in the view, such as stars, planets, and even comets and asteroids. Additionally, the Large Angle and Spectrometric Coronagraph (LASCO) on the SOHO spacecraft uses two filters for its images: an orange one sensitive to sodium and a blue one that can detect dust.

"When a comet or asteroid gets close to the sun, the intense radiation environment can release a lot of sodium from the object's surface," study co-author Karl Battams, who is the LASCO principal investigator at the U.S. Naval Research Laboratory, said in an NRL press release. "We can use LASCOs filters to look for signatures of sodium or the presence of dust, helping us understand the processes occurring on the surface of the comet or asteroid."

See original here:

Wow. Weird 'rock comet' 3200 Phaethon is way stranger than we ... - The Weather Network