"Fireball" meteorite discovered "Awesome sound and scary" The origin of the meteorite

"Fireball" meteorite discovered "Awesome sound and scary" The origin of the meteorite was August 5, 22:19

k10012553061_202008052201_202008052204.mp4

A woman from Chiba prefecture, who discovered last month that a wide range of "fireballs" had burned down and fell as meteorites, interviewed and asked about the situation at the time. I looked back.

At 2:30 am on the 2nd of last month, a particularly bright glowing fireball among shooting stars was witnessed over a wide area such as the Kanto region, and then this meteor that seemed to have fallen to the surface without burning up was Narashino Found in a city apartment.

According to the interview, the woman who found it was sleeping at home on the second floor of the apartment at that time, ``I suddenly woke up as I heard a loud noise like a metal hit by a barn'' I didn't go out because I was afraid someone had thrown a stone at home," he said.

In the morning, I found a stone about 4 cm in size in the shared corridor, and there was a dent in the railing in the corridor, but at that time I did not think it was a meteorite, so I kept it as it was. is.

However, the next day's news revealed that the meteor may have fallen into Chiba Prefecture, so I hurriedly picked it up, stored it, and contacted a nearby museum.

In the courtyard on the first floor, a woman found a piece of meteor about 5 cm in size, and then an expert examined it, and found another 15 pieces of finer meteor on another floor.

“I'm glad I knew it. I want the meteorites I have at hand to be exhibited at museums and other places,” said the woman.

Characteristics of the meteorites found

The meteorites found in Narashino City, Chiba Prefecture are brought to the National Science Museum for analysis.

The meteorite is mainly divided into two parts, one with a diameter of about 4.5 cm and a weight of 63 g, with a black and melted surface, and the rock part inside looks whitish.

The other is about 5 cm in diameter, weighs about 70 grams, and has a rusty brown part.

Rocks on the earth do not contain much metal, but meteorites are characterized by a large amount of metals such as iron, and the brown part of the meteorite found is considered to have been exposed to rain and rusted. I will. It is said to be the most common type of meteorite called "ordinary chondrite".

After conducting a detailed analysis at the National Museum of Science, we would like to apply for registration at the International Meteorological Society under the name "Narashino Meteorite".

Seiichi Yoneda, Group Leader in charge of the analysis of meteorites, said, “It was a very large fireball, so it is thought that larger fragments have not been found yet. If you find something that looks like a meteorite, ask a familiar person such as a science teacher at school to see it. , Please contact a museum if it is not a normal stone."

53rd meteorite in Japan

According to the National Museum of Science, this meteor is the 53rd confirmed in Japan.

53 meteorites that have been confirmed in Japan so far, such as ``Norkata Meteorite'' which was said to have fallen in Nogata City, Fukuoka Prefecture in 861 AD, and ``Komaki Meteorite'' found in Komaki City, Aichi Prefecture in 2018. there is.

In addition, there are more than 60,000 meteorites confirmed by international conferences in the world, and many are found in the Antarctic and desert areas, which are easy to find.

Meteorite is exchanged free of charge among experts for research, but in some cases it is sold among enthusiasts and collectors.

The meteor discovered this time is considered to be a type called "ordinary chondrite" that accounts for about 80% of the meteor discovered, and it is said that it is sold for several thousand yen per gram. And, "Carbonaceous chondrite" which is said to be close to the rock of asteroid "Ryugu" probed by Japanese asteroid explorer "Hayabusa 2" has few cases of discovery, tens of thousands of yen per gram, and the precious "Moon meteorite" It means that you can buy and sell for hundreds of thousands of yen per gram, and about 1 million yen for 1 gram of "Mars meteorite".

On the other hand, it is often said that asteroids and fragments of them fall into the Earth's atmosphere relatively often. The size of this meteor is thought to be less than 1 meter at the time of entering the atmosphere, and the number of particles falling to the earth is about 1 meter. If it is about 4 meters, it means that it is about one per year.

However, it will decrease as it gets larger, and once every 50 to 100 years if the diameter is about 20 meters, about 66 million years ago, the diameter of about 10 km that is said to have caused the extinction of dinosaurs is once every 100 million years. It has been with.

In the case of a meteorite that fell in Chelyabinsk Oblast in central Russia in 2013, it is estimated that an asteroid with a diameter of 17 meters and a weight of 10,000 tons entered the atmosphere, and it is thought to have been once every several decades. It is being done.

Origin of meteorite First estimated in Japan

This meteorite is known to have possibly come from any one of three specific asteroids, and it is attracting attention as the first case in Japan where the origin of the meteorite was estimated.

The three asteroids are "2020LT1", "2008WH96" and "2019NP1". All are small asteroids with a diameter of 100 meters or less. There are 53 meteorites found in Japan including this time, but this is the first case where the orbit can be identified and the origin is estimated from which asteroid came.

Why was it possible to infer the origin this time? That is the image of that fireball. Associate professor Shin Abe of Nihon University says that it was big that there were images taken from different points.

In the Kanto region, many cameras for observation were installed, and since it shined strongly, it was recorded in the images of various places. By analyzing it, we were able to analyze from which direction and in what direction it entered the atmosphere, and determine the original orbit.

Its orbit is an elliptical orbit from the inside of the earth to the outside of Mars, and we know the detailed angles. This orbit was in good agreement with the three asteroids when compared to approximately 23,500 asteroids.

In this way it was discovered that it could have come from any of the three asteroids.

Associate professor Abe says that it is possible to narrow it down by observing three asteroids and comparing them with the results of meteorite analysis. "There are few meteorites with an estimated origin in the world. So-called pedigree meteorites are extremely valuable," said Associate Professor Abe.