



Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

Photographer: Mila Zinkova

Summary Author: Mila Zinkova



Most everyone has heard about the Chelyabinsk meteorite that slammed into western Siberia last month. Not only were there perhaps a million people who witnessed this meteor but dozens of videos were taken of its early morning trace across a clear winter sky. Within hours these videos were available on the World Wide Web. However, few people know that there was a similar event 65 years earlier, in eastern Siberia. On the morning of February 12, 1947, a brilliant fireball was seen streaming across the sky, leaving a steamy, red trail in its wake. This fireball was described as being bigger than the Sun. The primary site of the meteor fall was discovered from a plane a day later when two pilots reported seeing fallen trees and craters in the snowpack. An expedition organized to look for remnants of the meteorite discovered 122 impact craters and thousands of pieces of shattered rock. The biggest crater was approximately 85 ft (26 m) in diameter and 20 ft (6 m) deep. Note that as with the Chelyabinsk meteorite, windows were broken with this fall as well. Shown above is a fragment (approximately 4 in or 10 cm wide) of the iron meteorite, from my collection, now known as the Sikhote-Alin Meteorite.

The meteorite itself exhibits thumbprints that are called regmaglypts as well as a natural hole. It's believed that these features were formed by the severe melting of the surface of the meteorite as it passed through the Earth's atmosphere. Partial melting produced the regmaglypts, but where the melting was complete the hole formed. Perhaps only 1 in 1,000 meteorites exhibits natural holes.

Of course, there were no digital cameras in 1947 to capture this phenomenon, but a painter who observed the fireball shared his amazement on canvas. "Fall of the Sikhote-Alin Meteorite." created by A. A. Medvedev was later reproduced in a post stamp (see inset).



Photo Details: Camera: OLYMPUS u1050SW,S1050SW; Focal Length: 9.1mm (35mm equivalent: 51mm); Aperture: f/4.0; Exposure Time: 0.0016 s (1/640); ISO equiv: 80; Software: Adobe Photoshop CS3 Windows.

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