Near-Earth objects and close calls

A fireball was spotted over the skies of Apulia in Southern Italy Wednesday evening. The meteor belongs to the South Taurids which originates from comet Encke.

Salento, a " fireball " sighted in the sky with a trail of light.

Around 7 p.m. on Wednesday, a bright trail of light was seen, followed by a loud roar. Experts from the Apulian Civil Defence said: "It was a fireball, a very bright meteor belonging to the South Taurids phenomenon, a meteor shower originating from the debris of the comet Encke", which burns on impact with the atmosphere.

The phenomenon lasted about 20 seconds and could be observed throughout the southern part of Puglia, around 7 p.m. The webcam in Ortelle (Lecce) captured the moment of the passage of the fireball in the sky. There were many reports on social networks from people who spotted the meteor.

The San Lorenzo Astronomical Park observed the phenomenon. The park's Facebook page reads: "We confirm the passage of the fireball (very bright meteor), which was also spotted from the area around our facility. The very bright trail, apparently green in colour, can almost certainly be traced back to the phenomenon of the South Taurids, the meteor shower that is occurring in these days. They are the remnants of the cometary tail of 2P/Encke that are being burnt up by the impact of the Earth's atmosphere and have the peculiarity of being very bright, albeit very rarely.

(Translated with DeepL)
Russia blew up a satellite with their new anti-satellite system, and now the space station has to be evacuated for a debris threat. The satellite they blew up was launched in the early 80's and weighed 2,000 pounds, and shares a very close orbit with the ISS.

A bright fireball streaked through the night sky over the Brazilian states of Bahia, Pernambuco and Sergipe.

Published on Nov 19, 2021 (3:41)

More here.

Bright fireball captured streaking in the sky above Popocatepetl volcano.

Published on Nov 20, 2021 (1:02)

A strange anomaly has been discovered in New Mexico, and behind it lies an even greater discovery

Scientists have discovered an unusual magnetic anomaly in the American state of New Mexico, not far from Santa Fe. The magnetism at that point was 10 times weaker than usual. And that led them to a much bigger discovery - how to find the places where meteorites hit, which are hidden.

Meteorite impact sites are seemingly easy to find, as they leave craters in the earth's surface. However, this is not always the case. Sometimes the places of impact are hidden by layers of dust, earth and vegetation over time. Now, thanks to a magnetic anomaly in New Mexico , scientists have found a way to discover them.

The magnetism at the point of impact is 10 times smaller​

Meteors enter the Earth's atmosphere at speeds of up to 72 kilometers per second , but slow down as they pass through it due to friction with the layers of the atmosphere. Thus is produced the bright light that we see in the sky when the meteorite becomes meteoroid (meteor into the atmosphere). Due to that friction, some of the meteorites burn up, while some shrink and hit the Earth's surface , becoming meteorites.

During the impact, a crater is created , but also other geological processes, such as high temperatures, high pressure, ejection of particles at high speed, all at the same time, writes "Science Alert".

During the collision, plasma is created , in which atoms are broken into electrons and positive ions.

"When a collision happens, it's a huge speed. That speed causes kinetic energy to be converted into heat, vapors and plasma, " said geologist Guenter Kletecka of the University of Alaska Fairbanks.

Scientists in New Mexico discovered that the plasma changed the magnetism of the rocks at the point of impact in a strange way , and that because of that it was 10 times weaker than usual, according to a scientific paper published in the scientific journal "Syantificate Report".

Rock structure indicating meteorite impact near Santa Fe in the mountains of Sangre de Cristo - Sputnik Serbia, 1920, 23.11.2021

A rock structure indicating a meteorite impact near Santa Fe in the Sangre de Cristo Mountains
CC BY-SA 3.0 / Wikipedia / Ikluft /

Traces of magnetic metals in the sediments during geological history aligned with the lines of the Earth's magnetic field and thus remained trapped in the rocks. This is a very low rate of magnetism , which can only be measured with special geological equipment.

Plasma made a "magnetic shield"​

When a shock wave occurs, such as a meteorite impact , the magnetism of the rock decreases, because the magnetized parts of the rock take over a good part of the energy shock.

"The shock wave produces more energy than the energy that retains magnetization in individual magnetic particles," the scientists state in their paper.
It is common for rocks to regain their level of magnetization after the shock wave has passed, but at the site of the impact, which is estimated to be 1.2 billion years old , near Santa Fe, not far from Route 475 in the Sangre de Cristo Mountains, magnetism has never returned.

Scientists believe that the plasma has made a "magnetic shield" that keeps the magnetized particles in such a state that they cannot align with the Earth's magnetic field, so the magnetization is 10 times less than usual.
This discovery could help scientists discover other places where meteorites hit, where the plasma could have caused a similar effect, although there are no clear traces on the Earth's surface that the impact occurred.

(auto-translation with Google)

Large asteroid stronger than nuke heading towards Earth late December

2018 AH is estimated to be around 190 meters long, similar to the Tunguska asteroid, meaning it would be far more powerful than a nuclear bomb.​


Published: NOVEMBER 26, 2021 15:20
Updated: NOVEMBER 28, 2021 08:56

A large asteroid the size of the Washington Monument is heading for Earth in late December that, if it impacts, would cause devastation far greater than an atomic bomb, according to NASA's asteroid tracker.

Known as 2018 AH, this asteroid is estimated to be about 190 meters wide and is set to pass by the Earth on December 27.

The asteroid is unlikely to hit the planet, however, expected to pass by at a distance of more than 4.5 million kilometers
. For comparison, the distance between the Earth and the Moon is around 384,000 km. – about a twelfth of that.

But 2018 AH has come by Earth before – and at a much closer distance.

Back in 2018, it flew past the planet at a distance of 296,758 km, three-quarters of the distance from the Earth to the Moon. It had gone unnoticed due to its dimness, and scientists therefore didn't see it coming.

Since that time, no asteroid of such size has come so close to the Earth – and none are expected to until 2028, when the massive, nearly kilometer-long 153814 (2001 WN5) will arrive. But it won't hit the planet either, being expected to pass at a distance of around 249,000 km – even closer than 2018 AH did.

But what would happen if an asteroid the size of 2018 AH struck the Earth?

Ordinarily, it can be difficult to accurately guess, as size often varies. But in this case, astronomers happen to have a very good idea of exactly how destructive it would be, because something like this happened before.

THE LAST time a large asteroid struck the planet was in 2013 in Russia, when a 17-meter asteroid exploded in the atmosphere.

But the last impact from an asteroid this big was in 1908 above the Podkamennaya Tunguska River in Russia, in what has now become known as the Tunguska event.

This asteroid is believed to have been around the same size as 2018 AH, if not smaller.

When the asteroid exploded in the air several kilometers above the area, it produced a massive 12 megaton explosion, causing widespread destruction for thousands of kilometers. That would make it about 800 times more powerful than "Little Boy," the approximately 15-kiloton atomic bomb detonated during World War II over Hiroshima, and 600 times more than "Fat Man," the 20-kiloton one detonated over Nagasaki three days later.

According to Encyclopedia Brittanica, a US government report at the time stated that Hiroshima suffered 135,000 casualties, or more than half of its population, and Nagasaki 64,000, a third of its population.

The death toll from the Tunguska event was extremely low, however, with only around three people thought to have been killed in it, due to how remote and sparsely populated the region was. But the damage was still evident, with about 80 million trees completely flattened, winds of around 27 km., a second bursting around and a loud noise heard far and wide. Tremors and air waves were felt as far away as even Washington and Indonesia.

The few eyewitness accounts that do exist recounted the terrifying explosion, strong winds, tremors and incredibly loud noises.

"The sky split in two and fire appeared high and wide over the forest," recounted a man who was about 65 kilometers south of the explosion.

"The split in the sky grew larger, and the entire northern side was covered with fire," he said. "At that moment I became so hot that I couldn't bear it as if my shirt was on fire; from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, and I was thrown a few meters. I lost my senses for a moment, but then my wife ran out and led me to the house.

"After that such noise came, as if rocks were falling or cannons were firing; the Earth shook, and when I was on the ground, I pressed my head down, fearing rocks would smash it," he said. "When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, and it damaged some crops. Later we saw that many windows were shattered, and in the barn, a part of the iron lock snapped."

The Tunguska event is the largest in recorded history – though larger prehistoric ones happened – and is one of the largest explosions ever recorded, far more powerful than many nuclear bombs.

If 2018 AH hit, it could cause something similar.

According to NASA, any asteroid 140 meters in diameter or larger could have a potentially catastrophic impact if it crashed into Earth.

The destructive nature of asteroids, even small ones, is something well-known to experts, with space agencies around the world monitoring for potential catastrophic impacts, as well as researching potential means of stopping them.

One method for possibly stopping the impact of an asteroid is through the use of deflection, which would mean launching something to slightly alter its path. The most prominent of these efforts is the Double Asteroid Redirection Test (DART) Mission currently underway, the result of efforts by NASA and the Applied Physics Laboratory.

In layman's terms, it means punching an asteroid with a rocket with enough speed to change its direction by a fraction of a percent.

The DART Mission is humanity's first real attempt at testing a defense against an asteroid impact and was launched towards the Didymos binary asteroid system.
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