lunedì 4 giugno 2018


SMALL ASTEROID HITS EARTH: On Saturday, June 2nd, astronomers working with the Catalina Sky Survey in Arizona discovered a small asteroid (2018 LA) near the orbit of the Moon. Hours later, it hit Earth. The boulder-sized space rock entered the atmosphere traveling 38,000 mph (17 km/s) and exploded over Botswana at 6:44 p.m. local time. A video camera at a farm near Ottosda, South Africa, recorded the explosion. It was impressively bright even at a distance:
The explosion sent waves of low-frequency sound (infrasound) rippling through the atmosphere, and it was detected by an infrasound monitor in South Africa, deployed as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. Meteor expert Peter Brown of the University of Western Ontario analyzed the signals and came to these conclusions about the explosion:
"The yield was in the range 0.3 to 0.5 kilotons of TNT," he says. "That corresponds to a 2 meter diameter asteroid."
As asteroids go, that's very small. It posed no significant danger to objects on the ground as it disintegrated almost wholly in the atmosphere. Fragments may yet be found on the ground and recovered for sale or scientific study.
The real significance of this event is that it highlights the growing capability of modern sky surveys to discover asteroids targeting Earth. Even small faint space rocks are being caught in the net. Boulder-sized impactors have been discovered hurtling toward Earth three times in the past 10 years: 2008 TC3 exploded over northern Sudan on Oct. 7, 2008; 2014 AA burned up above the Atlantic Ocean on Jan. 1, 2015; and now 2018 LA. In each case, the warning was a day or less. Larger asteroids may be seen at a greater distance, however, allowing for more lead time.

Realtime Space Weather Photo Gallery

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