NOTABLE ASTEROID IMPACTS ON PLANET EARTH

 

Hungarian astronomer Kristian Sarnicki at the Beszkisto mountain station – part of the Konkuli Observatory near Budapest – discovered a small asteroid on March 11, 2022, just two hours before it collided with Earth’s atmosphere. The asteroid’s width is believed to have been about 10 feet (3 metres). Now named 2022 EB5, this object entered Earth’s atmosphere north of Iceland at 21:22 UTC on March 11. Orbit simulation expert Tony Dunn commented on Twitter (@tony873004): When 2022 EB5 hit Earth north of Iceland this morning, it became the fifth asteroid to be discovered before hitting Earth 2014 AA, 2018 LA, 2008 TC3, and 2019 MO are the other four. It is estimated that the asteroid was moving at a speed of about 11 miles per second (18.5 km/s). This is in contrast to the speed of Earth in its orbit of 18 miles per second (30 km/s).

All through Earth’s history, there have been numerous instances of near-Earth objects (NEOs) impacting our planet, either reaching the surface or exploding above Earth from the intense energy released as the object passes through the atmosphere. Asteroid impacts are natural processes that form the surface of our planet, such as volcanoes. The vast majority of these effects were from very small objects, but there were some pretty remarkable exceptions.

Chelyabinsk event

In 2013, an asteroid with a diameter of about 20 meters entered the Earth’s atmosphere over the city of Chelyabinsk in Russia. It exploded while still in the air, releasing the same amount of energy as 500 kilotons of TNT. Fortunately, it exploded 30 kilometers above the earth’s surface and did not cause direct damage. However, it created a shock wave that injured 1,500 people and destroyed 7,200 buildings in six cities. Most injuries were caused by curiosity: people saw the bright flash and walked to the windows to look outside. 

The shock wave, traveling at a speed slower than sound, arrived later and smashed the windows, injuring people with flying glass. In 1908 an asteroid or comet 30 meters in diameter entered the atmosphere and exploded above Earth in Tunguska, Russia. The eruption destroyed nearly 80 million trees over an area of   2,150 square kilometers (830 square miles). The power of this explosion was estimated to be about 1,000 times stronger than the explosion of the atomic bomb in Hiroshima. Had this happened in an urban area, that city would have been completely destroyed. Fortunately, it happened in a remote part of Siberia, and no one is believed to have been killed.

An impact of this magnitude had devastating effects, and the geological record gives us some indication of what happened. The asteroid collided with the water, causing giant tsunamis to reach from southeastern Mexico all the way to Texas, Florida and even the shallow inner ocean that covered what is now the Great. The explosion had thrown chunks of the asteroid and Earth so far that they would have briefly left the atmosphere before falling back to Earth.

Like millions of falling stars, all of this material could have been heated up to glow upon re-entry, heating up the Earth’s surface and igniting wildfires. It is possible that all the forests of the earth have been burned. Meanwhile, massive shock waves would have triggered global earthquakes and possibly volcanic eruptions. A cloud of dust, ash and superheated steam would have scattered from the crater as the impactor smashed underground in less than a second. This dust could have covered the entire surface of the Earth for up to a decade, creating a harsh environment for living organisms. Perhaps most importantly, dust can remain stuck in the atmosphere, blocking the sun and interrupting the photosynthesis of plants on which the entire food chain depends, as well as cooling Earth’s temperatures for many years.

65 million years ago, an asteroid about 10 to 15 kilometers (6 to 9 miles) in diameter struck Earth in what is now Mexico. The impact killed 70% of all species on Earth, including dinosaurs.

Although massive shocks like the one that destroyed the entire planet 65 million years ago are rare, NEOs of various sizes can pose serious threats. An impact on or over a densely populated city can cause millions of deaths, and an impact on the water can cause massive flooding on the coasts. Any significant impact would result in widespread damage, injury and death, and would create unparalleled humanitarian and refugee crises worldwide.

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