From NS: “Why Morocco loves its meteorites”

NewScientist

New Scientist

30 June 2017
Sandrine Ceurstemont

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A hotspot for space rocks. Sandrine Ceurstemont

In Morocco’s High Atlas mountains, the twin lakes of Isli and Tislit (nicknamed the Moroccan Romeo and Juliet) have an unusual origin. Abderrahmane Ibhi from Ibn Zohr University in Agadir found strong evidence in 2013 that they were impact craters, formed when an asteroid hurtling towards Earth split in two about 40,000 years ago. “It was over 100 metres wide,” says Ibhi. “It’s the biggest asteroid to fall in Morocco.”

Large space rocks can cause destruction or alter the landscape if they hit Earth. Today, the world’s Asteroid Day, Ibhi gave a talk about how to protect our planet from killer asteroids. “When they are over 10 metres wide, they can be dangerous,” he says.

Luckily, space rocks rarely hit Earth. And double impacts are even less common: there are only three other known cases worldwide. But in recent years, the already otherworldly rocky land and desert close to Tata in southern Morocco has been defying the odds. From chunks of asteroids to pieces of the moon, more space rocks have been recovered in Morocco than in other countries of a similar size, with 95 per cent of them coming from around Tata.

Rare finds

It has been home to several rare finds, too. The most famous – the Martian meteorite of Tissint – blasted through the night sky in July 2011, scattering pieces that were collected over the following months.

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http://www.mirror.co.uk/news/technology-science/science/tissint-martian-meteorite-which-landed-in-morocco-1373528

It’s one of five rocks from the Red Planet ever to be found on Earth, and the first to carry traces of Martian soil.

Ibhi and his team have been trying to work out why the area is such a hotspot. One reason seems to be the landscape: meteorites are easily revealed by windswept sand, in which their dark colour also makes them stand out. And a dry climate helps preserve them far better than a humid one.

Then there’s the well-distributed population, which gives people a greater chance of stumbling upon them. In Tata, several villages are close together and many nomads live in the desert, explains team member Fouad Khiri. In addition, Morocco’s political stability is a plus, making it safer than in other countries to wander around searching for meteorites.

But the biggest factor is a surprise: local knowledge. Since 2006, Ibhi has been organising workshops to teach people how to identify space rocks. Many nomads are now aware, for example, that looking for a particular combination of features that may mark them out is key.

One of the telltale signs is a black skin, or fusion crust, formed by the fiery journey through the atmosphere. But desert rocks can appear similar, given that they too can have a dark surface from the extreme heat. Looking for marks that resemble thumbprints, caused by wind sculpting the rock during its journey, is a helpful clue.

Space rocks from asteroids – the most common type – also have circular grains across their surface composed of molten minerals. “I always bring meteorites along so that people can take a close look and feel them,” says Ibhi.

See the full article here .

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