We finally know how the mysterious Geminids meteor shower originated Ars Technica

Image of streaks in a night sky.
Zoom in / The Geminids put on a show every year.

Every year, skywatchers can watch the Geminids dart across the night sky from mid-November to late December. However, this meteor shower is highly unusual, and not just because it’s one of the easiest to see.

Meteor showers usually come from comets flying close to the sun. Comets are made of frozen gas, dust and rock, and the sun’s heat vaporizes some of that gas and releases it into space, washing away the debris that eventually falls to Earth. But the Geminids are exceptional because they came from an asteroid instead of a comet. Asteroid 3200 Phaeton is the source of this debris trail, but asteroids aren’t affected by solar heat in the same way as comets, so it’s not clear why Phaeton left a debris trail.

NASA scientists who have analyzed data from the Parker Solar Probe space agencies have finally found the most likely answer to the mystery of the formation of the Geminids: a catastrophic event. The Geminids may have formed through more violent and catastrophic destruction of bodies transiting very close to the Sun, scientists said in a study 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 the Geminids came to be? Its orbit takes it right through the core of the Geminids at perihelion, or the point at which they and 3200 Phaeton come closest to the Sun. As he flew through the meteor shower, Parker was bombarded by specks of dust that emitted electric on impact. These signals were picked up by his FIELDS instrument, designed to measure (among other things) electric and magnetic fields. The speed with which the specks of dust went and the force with which they struck gave an indication of their mass idea of ​​what could have been behind the formation of the Geminids.

Parker’s data, coupled with simulations and Earth observations, convinced the science team, led by planetary scientist Wolf Cuvier, that the Geminids weren’t consistently detaching from 3200 Phaetons. Phaeton and the resulting debris could be the result of a collision or explosion that tore apart a much larger body, perhaps a comet. Cuvier and his team think it’s also possible that the same collision also produced two nearby asteroids.

Such a collision would also explain another mystery: the mass of the Geminids. Together, they are at least as massive and possibly more massive than their parent asteroid. 3200 Phaeton loses some material in orbit, but not enough to explain the mass of the Geminids.

The mass of the Geminid stream is estimated to be on the order of or greater than that of the parent body 3200 Phaethon, suggesting that the stream formed in a possibly catastrophic event that lost a large amount of mass over a period of time relatively short about 2,000 years ago, the scientists in the study also said.

Catastrophic

Cuvier’s team used Parker’s data to model how the Geminids potentially formed. Taking into account the impacts of the dust particles that crashed into the spacecraft, they ran several disaster simulations. The first model simulated a typical catastrophic asteroid destruction event; the second involved a more violent event that would have scattered faster moving debris over a larger area. The third model guided the formation of a meteor shower from a comet.

It turned out that the most likely scenario was also the most violent, and this has been confirmed by observations of the Geminids from Earth. Would such a crushing event have hurled space rocks to the Earth’s surface thousands of years ago? As ominous as that sounds, that would have been highly unlikely. None of the three models showed debris hitting our planet.

As sensitive as Parker’s FIELDS tool is, there are still some things it can’t tell us. The kind of catastrophe that formed the Geminids is still unknown. Whether it was a collision or a gaseous explosion would have impacted the shape and width of the debris flow. While Parker can’t imagine its structure directly, further missions could. The upcoming JAXA DESTINY+ mission will head straight for 3200 Phaeton after launch in 2024. It could perhaps shed more light on how the Geminids came to be by making more direct observations. Until then, we’ll keep staring at the winter sky and wondering.

Planetary Science Journal, 2023. DOI: 10.3847/PSJ/acd538 (DOI information).

Elizabeth Rayne is a writing creature. Her work has appeared in SYFY WIRE, Space.com, Live Science, Grunge, Den of Geek and Forbidden Futures. When she’s not writing, she shapeshifts, draws, or cosplays as a character no one has ever heard of. Follow her on Twitter @quothravenrayne.

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Image Source : arstechnica.com

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