We finally know how the mysterious Geminid meteor shower originated – Ars Technica

Every year, skywatchers can gaze upon the spectacle of the Geminids creeping across the night sky from mid-November through late December. However, this meteorite is very unusual, and not just because it is one of the easiest to see.

Meteor showers usually originate from comets that fly by the sun. Comets are composed of frozen gases, dust, and rock, and the sun’s heat evaporates some of this gas and releases it into space, removing debris that eventually falls to Earth. But the Geminids are exceptional because they originated from an asteroid rather than a comet. Asteroid 3200 Phaeton is the source of this debris, but asteroids are not affected by solar heat like comets, so it is unclear why Phaeton left a trail of debris.

NASA scientists analyzing data from the space agency’s Parker Solar Probe have finally discovered the most likely answer to the riddle of how Gemini formed: a catastrophic event. Scientists said in Stady It was recently published in The Planetary Science Journal.

in pieces

So how did the Parker Solar Probe, designed to study the Sun, provide hints about how Gemini was born? Its orbit takes it directly through the core of the Geminids at perihelion, or the point at which 3200 Phaetons approach the Sun. As it flew through the meteor shower, Parker was bombarded with dust grains that gave off electrical signals upon impact. These signals were detected by the FIELDS instrument, which is designed to measure (among other things) electric and magnetic fields. The speed at which the dust grains were moving and how strong they were – an indication of their mass – gave an idea of ​​what could be behind the formation of the gemini.

Parker’s data, combined with simulations and Earth observations, convinced the science team, led by planetary scientist Wolf Cuvier, that the Geminids did not consistently separate from 3200 Phaeton. Phaeton and the debris that resulted from it may have been caused by a collision or explosion that shattered a much larger object, possibly a comet. Cuvier and his team think it’s also possible that the same collision produced two nearby asteroids.

Such a collision might explain another mystery: Gemini’s mass. Together, they are at least the same mass and possibly more than the parent asteroid. 3200 Phaeton does lose some material in orbit, but it’s not nearly enough to calculate the Geminids’ mass.

“The Geminids stream’s mass is estimated to be on the order of or greater than that of the parent body 3,200 Phaethon, indicating that the stream was formed in a potentially catastrophic event that dumped a large amount of mass in a relatively short period of time,” the scientists also said in the study.

disastrous

Cuvier’s team used Parker’s data to come up with models of how Geminids form. With the effects of dust particles hitting the lander in mind, they ran several disaster simulations. The first model simulates a typical asteroid destruction event; The second involved a more violent event that would have scattered faster moving debris over a wider area. The third model led to the formation of a meteor from a comet.

It turns out that the most likely scenario was also the most violent, and this was supported by the Geminids’ observations from Earth. Would this destruction event have sent space rocks crashing to Earth’s surface thousands of years ago? No matter how threatening it looked, that was extremely unlikely. None of the three models showed any debris hitting our planet.

No matter how sensitive the Parker FIELDS tool is, there are still some things it can’t tell us. What kind of calamity formed the Geminids is still unknown. Whether it is a collision or a gas explosion, it will affect the shape and width of the debris stream. While Parker can’t directly film her structure, other assignments may be possible. Next JAXA Destiny + mission It will indeed be heading directly to the 3200 Phaeton after its launch in 2024. It could clarify more about how the Geminids came to be by making more direct observations. Until then, we’ll continue to stare at the winter sky and wonder.

Planetary Science Journal, 2023. DOI: 10.3847/bsj/acd538 (About DOIs).

Elizabeth Raine Creature Writes. Her work has appeared on SYFY WIRE, Space.com, Live Science, Grunge, Den of Geek, and Forbidden Futures. When she’s not writing, she’s either shape-shifting, drawing, or masquerading as a character no one has ever heard of. Follow her on Twitter: @hravenrayne.