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The rocks that make up the Geminid meteor shower A new study suggests that meteorites that occur towards the end of each year may have been created by chaotic events 18,000 years ago, making them about 10 times older than previous estimates. ing.
The Geminid meteor shower is named after the constellation Gemini, the location in the sky where the meteors appear. However, meteorites actually occur in 3200 Phaetonstrange blue asteroid Wandering along a watermelon-shaped orbit, it will come within just 0.14 astronomical units of the Sun, or about one-tenth of the distance between Earth and the Sun. At this point in its orbit, the 3.2-mile (5.1-kilometer) wide Phaethon acquires a strange, comet-like tail.
Astronomers have long believed that the tail is made up of rocky debris that forms a dust cloud that produces the Geminid meteor shower. However, recent observations contradict this, showing that the particles in the current tail are a thousand times smaller than the bead-sized rocks of the Geminid meteor shower; vaporized sodium, not dust. Therefore, the rocky cloud that causes the Geminid meteors must have formed at some point in the past. But when and how?
One theory is that Phaeton is thought to have deposited debris from the Geminid meteor shower near Earth about 2,000 years ago, when the rock was closest to the sun, said the study’s lead author. Hanbin Cho, a graduate student in astronomy at Seoul National University in South Korea, told Live Science. Email. But Joe said that if Phaethon had produced the Gemini meteor shower through comet-like activity, the asteroid would have had to contain huge amounts of ice to eject the debris, but computer models suggest He pointed out that this shows that the possibility of that happening is low.
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Instead, Joe and co-author Masaki Ishiguro, a professor in the Astronomy Program at Seoul National University, focused on another mechanism: rotational instability. Joe explains that in such a process, solar radiation “pushes” the asteroid, causing its rotation to slowly accelerate, and after a few million years, centrifugal force overcomes the gravitational force that glues the asteroid’s smallest components together. He said it would rotate fast enough to. . In the case of Phaethon, such an instability would cause it to partially fragment, producing millions of pieces of gravel – perhaps the Geminid meteor shower.their study The paper has been accepted for publication in “Astronomy and Astrophysics” magazine.
To test their theory, the researchers worked backwards from the present to determine Phaethon’s position and velocity over the past 100,000 years. They then selected his nine time periods, each 1,000 years long, and simulated an asteroid ejecting rocky debris within that time period.
In these simulations, Phaethon is modeled as a 261 trillion pound (116 trillion kilogram) sphere, spinning fast enough to dislodge about 300,000 pieces, primarily from its abdomen. This would mimic the behavior of an asteroid if its rotation was destabilized by solar radiation. The researchers then traced the path of this debris over thousands of years, taking into account the gravitational forces from all the planets in the solar system.
Simulations revealed that a super-rotating Phaethon may have produced the Geminid meteor shower. First, their results suggest that the total mass of the meteors averages 10 million tons, which is consistent with predictions made using NASA forecasts. parker solar probe. Furthermore, the two simulations almost exactly mimicked the observed orbits of the Geminid meteor shower.
In these models, Phaethon’s mass ejection occurred 18,000 years ago, leading the researchers to conclude that this is the time when the particles responsible for the Geminid meteor shower were likely thrown into space. I am. However, the simulations also revealed that these were only some of the debris created during this event, and that the combined gravity of Venus and Earth was directed toward us about 4,000 years ago.
Researchers hope that DESTINY+ mission to Phaethon, JapanThe spacecraft, scheduled for launch in 2025, will likely find evidence of such rotational instability.
After losing mass, Phaethon likely slowed down due to conservation of angular momentum, Joe said.but new observations The results suggest that space rocks are spinning faster again, reducing their rotational period by 4 milliseconds each year. That means a new meteor could be born someday, but only in millions of years.
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