The Sutter’s Mill meteorite was seen by many eyewitnesses over the foothills of the Sierra Nevada range in California. A new, detailed study has traced the origins of this rock with unusual precision, and it has been revealed that it came down at record-breaking speed.
The scientists published their findings in the journal Science¹. Most of the 40,000 meteorites that have been recovered came from the asteroid belt, located between the orbits of Mars and Jupiter. However, in the case of the Sutter’s Mill meteorite, astronomers were able to find a more precise origin.
The scientists used records of the meteorite from weather data, which is commonly used to track rainfall in real time, and combined it with photographic and video images, as well as other data. The researchers then reconstructed the trajectory of the meteorite, and found it to be similar to comets from the outer reaches of the asteroid belt, near Jupiter’s orbit.
The meteorite entered Earth’s atmosphere at a speed of 28.6 kilometers per second, which makes it the fastest on record. A chemical and physical analysis of the meteorite revealed that it was a relatively rare carbonaceous chondrite meteorite, which are seen as time capsules since they have barely altered since the formation of the Solar System, 4.5 billion years ago.
Carbonaceous chondrites are thought to be especially prevalent in the outer reaches of the asteroid belt, and the California rocks confirm that theory, being a rare case for which both the composition and the provenance are known. Usually, asteroids are seen through a telescope, which reveals location but gives only partial information on its composition, or the asteroid fragments that fall on Earth as meteorites are analyzed in great detail, but in most cases we have no idea where in space they originated. The Sutter’s Mill meteorite is a rare case where we get to know the whole story.
- Jenniskens, P. et al. Science 338, 1583–1587 (2012).