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Astronomers Have Discovered The Smallest Asteroid We Know Of, And It's Only Slightly Bigger Than A Person


Jonathan O'Callaghan

Senior Staff Writer

The asteroid was too small to get a picture of, so here's an artist's impression of an asteroid instead. Rasica/Shutterstock

Asteroids can vary in size from a few tens of meters across to several kilometers. But this latest discovery pales in comparison, being the smallest we've ever found.

Measuring a paltry 2 meters (6 feet) across, just slightly bigger than an average person, the asteroid is called 2015 TC25. In October 2015, it flew past our planet at a distance of just 128,000 kilometers (80,000 miles), just a third of the distance to the Moon. And as it did so, an array of telescopes were able to get as much data on it as possible.


The irregularly shaped asteroid was described in a paper published in The Astronomical Journal.

"This is the first time we have optical, infrared and radar data on such a small asteroid, which is essentially a meteoroid," lead author Vishnu Reddy from the University of Arizona said in a statement. "You can think of it as a meteorite floating in space that hasn't hit the atmosphere and made it to the ground – yet ."

Radar imaging of asteroid 2015 TC25

Studying these small objects is important, because some of them make their way to the surface of Earth. By studying them in space, we can essentially look at them before and after they enter our atmosphere. For reference, the Chelyabinsk meteor that exploded over Russia in 2013 was less than 20 meters (65 feet) in diameter.


2015 TC25 was especially of interest because it was found to be extremely bright. According to observations by the NASA Infrared Telescope Facility and Arecibo Planetary Radar, it reflects 60 percent of sunlight that falls upon it.

That puts it in a rare class of asteroids known as aubrites, which have an abundance of very bright minerals such as silicates. Only one in every 1,000 meteorites that makes its way to Earth is thought to be an aubrite.

This asteroid was also one of the five smallest to have its rotation rate measured, which came in at one spin every 133 seconds.

As for where it’s come from, well, that’s not clear at the moment. But Reddy said he thought it may have been chipped off a larger asteroid in the asteroid belt between Earth and Mars, called 44 Nysa, when another asteroid hit it.


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