When Allende hit Earth... Science

Born with the solar system

Fragment of the Allende meteorite.   | Photo Credit: Wikimedia Commons

At about the size of an automobile, it was travelling towards the Earth at a speed of more than 10 miles per second. And then when it was over 11 miles above the surface of the Earth, it burst and broke up into thousands of pieces. Sounds eerily similar to the Columbia disaster that we discussed last week? Don’t you worry? This one had no casualties, for it wasn’t a disaster, but in fact the most important stony meteor shower on record.



Know it? Or know it!
X is believed to be among the oldest minerals in the solar system and belongs to a class of refractory minerals that could have only formed in the infant solar system. X honours Pan Gu, who is believed to be the first living being in Chinese mythology and created the world by separating yin (earth) and yang (sky). X is mentioned in this article. X? Send your answers to ganesh.a.s@thehindu.co.in with your details. [subject: Allende]
The sky lit up early on February 8, 1969 for many in Mexico. Rumbling out of the southwest, the meteor tore through the sky like a large fireball, increasing in luminosity and noise level. Approaching the village of Pueblito de Allende in the state of Chihuahua, Mexico, it exploded at 1:05 local time and the pieces were spread over a 300 km area.

The Allende meteorite, named after the village, thus had a vast strewnfield (the meteorite’s dispersal area). Scientists, who took the help of the locals, including children, collected a ton of material - from those that were as little as a gram to a stone that weighed 110 kg. While fragments have found their way to museums and universities throughout the world, an unknown amount is also in the hands of private collectors.

Gifts from the space

Some of you would have already realised that this happened in the same year when man left his mark in the moon. As part of the preparation for the same, NASA had set up laboratories across America with the latest equipment, in order to analyse what were to be the first ever lunar materials.

Allende’s arrival was as if Christmas had come early for these scientists. And it so happened that the gifts on offer were in fact more valuable than the rocks that were later brought from the moon.

Why rare

A rare type of meteorite, Allende is classified as a Type III carbonaceous chondrite - among the oldest known matter in our planetary system. Studying it has opened up new vistas regarding the formation of our solar system.



Last week’s answer
Kalpana Chawla was the Indian-American who lost her life in the Columbia disaster. We received plenty of correct answers. Swastik Shee of Class 8, DAV Public School-Dwarka, New Delhi, was among the first to get it right. Congratulations!
Slicing open the meteorite revealed small white objects, unlike anything that had been studied before. Now called calcium-aluminium inclusions, or CAIs, they are mixtures of high-temperature oxides and silicates of calcium, aluminium and titanium. More importantly, with a radiometric age of 4.567 billion years, they represent some of the first solid matter to form in the solar system, swirling as dust around the young sun.

Best studied meteorite
As recently as 2012, researchers at the California Institute of Technology discovered a new mineral named panguite, and eight others by studying Allende. Panguite, which belongs to a class of refractory minerals, was formed under the extremely varied pressures and high temperatures associated with the early solar system, making it among the oldest minerals.

In fact, ever since Allende landed in 1969, it has been extensively studied, with additional publications about the meteorite appearing every year, sometimes as often as a month. The birth of cosmo-chemistry, a new branch of science at the intersection of geology, astrophysics and astronomy, and the study of meteorites becoming an integral part of earth science, are after effects of Allende. No wonder they call it the best studied meteorite in the world.


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Printable version | Oct 21, 2021 10:30:14 AM | https://www.thehindu.com/in-school/sh-science/born-with-the-solar-system/article8206062.ece

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