What is a meteorite? A question that sounds very familiar, seemingly easy, yet it has puzzled many people.
What is a Meteorite?
According to Wiki, meteorite, in Sino-Vietnamese terms, means “heavenly stone”, but currently, in Vietnamese, it is used inconsistently to refer to various celestial objects with completely different natures.
A meteorite (meteoroid) is a natural object from outer space that impacts the surface of the Earth. When it is still in space, it is called a meteoroid. When a meteorite falls from outer space into the Earth’s atmosphere, compressive pressure causes it to heat up and emit light, which may involve the burning of its outer layer. This phenomenon creates a “shooting star” that appears as a bright point, often with a tail trailing away from the Earth. Some meteorites, if large enough and dense enough to avoid vaporization, can reach the Earth’s surface, leaving behind solid fragments or lumps that are still referred to as “meteorites” (meteorite).
A meteorite (meteoroid) is a natural object from outer space that impacts the surface of the Earth.
Additionally, unaltered meteorite materials that have not undergone melting or transformation from the parent meteoroid are called chondrites.
Typically, when meteorites travel at high speeds and collide with the surface of a planet or asteroid, they leave behind debris or marks from the impact. We can clearly see images from space taken by NASA showing the craters on the Moon, which lack wind, or on Mars.
Worldwide, many sites have been found where traces of meteorite impacts have been left. As of mid-2006, around 1,050 meteorite samples from impacts were recorded, with approximately 31,000 documented accounts regarding meteorites.
Identifying Meteorites
According to Mr. Nguyễn Đức Phường from the Vietnam Astronomical Society, meteorites have unique characteristics that can be visually distinguished. “The surface of meteorites is often black, smooth, and shiny. Some meteorites may have round, smooth indentations or cracks due to erosion and combustion in the atmosphere,” he stated.
The Willamette Meteorite found in the U.S. in 1902. (Photo: Wikipedia).
Moreover, the cross-section of a meteorite will reveal many small grains with diameters of 1-3 mm.
- Regarding weight, meteorites of the same size tend to be heavier and denser than regular rocks. Meteorites typically contain a certain amount of iron, making them magnetic; thus, they can be identified using a magnet.
- Regarding color, meteorites are often black or have a blackish-yellow hue due to oxidation.
According to the book series “100,000 Whys,” the main components of meteorites are iron and nickel, with iron accounting for about 90% and nickel 4-8%. The amount of nickel in naturally occurring iron on Earth is not as high. If the cross-section of an iron meteorite is polished and nitric acid is applied, distinctive patterns resembling floral designs will appear. This is due to the uneven distribution of components within the iron meteorite; areas with high nickel content resist acid corrosion, creating these patterns. This is another way to identify a meteorite.
However, according to Mr. Phường, if someone possesses a meteorite, it is best to consult an expert for accurate assessment.
The Destructive Power of Meteorites
Throughout its existence, Earth has endured many catastrophic events, leaving behind horrific traces. Over time, the signs of meteorite impacts on Earth include:
Vredefort Dome Impact Crater
The catastrophic event on Earth caused by a meteorite occurred about 2 billion years ago in the Vredefort Dome area, southwest of Johannesburg, South Africa. This is considered the largest meteorite impact ever discovered, resulting from the collision of an estimated 10 km-sized rock traveling at approximately 36,000 km/h, leaving a crater about 300 km wide known as the Vredefort Dome. According to scientists, this event took place before humans and most plants and animals existed. The only living organisms at that time were algae similar to modern green moss found in dams.
The Extinction of Dinosaurs
The largest explosion ever recorded on Earth, leaving ample geological evidence, is known as the Chicxulub Extinction Event. This event occurred about 65 million years ago due to a meteorite impact, creating the Chicxulub crater offshore of the Yucatan Peninsula in southeastern Mexico. The explosive force of this event is estimated to be equivalent to 96 trillion tons of TNT (96 Teratons), or about 1.7 million Tsar bombs, which refers to the hydrogen bomb tested by the Soviet Union on October 30, 1961, with an explosive yield of 57 million tons of TNT. This devastating impact created a roughly 110-mile-wide crater known as the Chicxulub crater, ejecting tons of dust into the atmosphere, causing earthquakes, tsunamis, fires, acid rain, and rendering most of Earth’s land barren, effectively wiping out life on Earth. Notably, the dinosaurs, which dominated the planet at the time, were completely eradicated.
Vredefort Dome Impact Crater.
Chicxulub crater offshore the Yucatan Peninsula. (Source: Howstuffworks)
Hoba Meteorite
The heaviest meteorite known as Hoba was found on Earth in a farm in Namibia, Africa, believed to have landed more than 80,000 years ago. This meteorite covers an area of over 6.5 square meters and weighs an estimated 66 tons, consisting of about 84% iron and 16% nickel. It is currently regarded as the largest natural iron mass on Earth. Contrary to its gigantic size, the Hoba meteorite did not leave any dent, which many scientists explain as it having passed through the Earth’s atmosphere at a very shallow angle. In 1955, the Namibian government decided to recognize this meteorite as a national historical monument, and it has since become a famous tourist attraction.
Barringer Crater
A crater approximately 170 meters deep and about 1.6 km in diameter, known as Barringer Crater, is believed to have been formed 50,000 years ago. This meteorite, with an estimated diameter of nearly 50 meters, struck the Arizona desert in the United States at a speed of approximately 46,000 km/h, causing an explosion estimated to be equivalent to 150 times the atomic bomb dropped on Hiroshima, obliterating all life over several hundred square kilometers.
Barringer Crater. (Source: Howstuffworks)
Tunguska Event
The largest recorded meteorite explosion on Earth occurred in 1908 in the Tunguska region of Russia. This event remains a topic of heated debate as there were no remaining traces of a meteorite impact. This lack of evidence has posed significant challenges for scientists in determining the true origin of the meteorite fragment. The explosion destroyed around 80 million trees over an area of 2,150 km2, incinerating all homes and livestock within a 13-mile radius. Scientists continue to study the area affected by the blast, but no meteorite fragments or craters have been discovered.
Destruction caused by the meteorite in Siberia (Russia) in 1908. (Source: Howstuffworks)
Chelyabinsk Meteorite
The most recent meteorite incident is the Chelyabinsk meteorite, which fell in Russia in 2013. Measuring 17 meters, it exploded at an altitude of 30 km, generating energy 300 times greater than the atomic bomb dropped on Hiroshima in 1945. This explosion shattered 1,000 windows and injured 500 people due to flying glass; major scientific centers in the United States and Russia are focusing on researching response solutions.
