Scheila, officially called 596 Scheila, is about 70 miles in diameter – that’s miniscule by planetary standards but a significant size when compared to many objects in the Asteroid Belt. The Asteroid Belt is that vast, rocky plain that orbits the sun between Mars and Jupiter.
Astronomers noticed in late November that Scheila suddenly and noticeably brightened – doubled in intensity and took on a comet-like glow. Telescopes and instruments were quickly brought to bear on the event.
Intense research, the results of which will be published in May’s Astrophysical Journal, revealed that she’d been hit by another, smaller asteroid. The smaller body crashed into Scheila at 11,000 mph, and at an angle of about 30o – creating a crater that was as much as 1,000 feet across and sending a plume of debris off either end of the asteroid.
The dust plumes were reflected in the sunlight, causing the asteroid’s brightness to noticeably increase. The plumes also obscured astronomer’s ability to see details on the asteroids surface, giving it a comet-like appearance. The plumes were whipped away a few weeks later by the solar wind, that never ending bellow of radiation produced by the sun’s nuclear fire.
The plumes, however, revealed much about the asteroid’s interior. When NASA’s Deep Impact Probe punched an 800 pound bullet into the comet Tempel 1 back in 2006, the collision raised a cloud of ice and dust. The impact on Scheila, however, was as much as 10,000 times more massive than that, and kicked up a cloud of rock and dust but no ice, indicating that the asteroid is of an entirely different structure than most comets.
The Scheila impact raised as much as 660,000 tons of dust.That’s twice the weight of the Empire State Building.
Astronomers were very fortunate to have spotted the impact. The relentless solar wind quickly erases collision dust clouds, leaving gaping craters and rough, ragged rock fragments as our only clues to the violent nature of Asteroid Belt.
You can learn more about Scheila’s earth-shattering experience at NASA’s News page.
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