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Halloween Asteroid Likely a Dead Comet

Oct. 30, 2015
Tucson, Ariz. -- A “Halloween” asteroid that will pass close to Earth tomorrow could actually be a dead comet, according to research by Vishnu Reddy of the Planetary Science Institute.

On Halloween – Oct. 31 – asteroid 2015 TB145, considered a potentially hazardous object, will pass the Earth as close as 300,000 miles, or just 25 percent beyond the Moon's orbit. Understanding the composition of these objects is important to understand how such threats might be mitigated, but also from where in the solar system they originated. The asteroid, 600 meters in diameter, poses no threat to Earth at this time.

On Oct. 30 Reddy, a PSI Research Scientist, captured the body’s spectrum and determined it to be similar to dark carbonaceous meteorites. Astronomers had suggested that the body could be a comet based on its orbit.

"We found that the object reflects about 6 percent of the light it receives from the Sun. That is similar to fresh asphalt and while here on Earth we think that is pretty dark, but it is brighter than a typical comet which reflects only 3 to 5 percent of the light,” said Reddy, who made his observations using the NASA Infrared Telescope Facility in Mauna Kea, Hawai’i. "That suggests it could be cometary in origin – but as there is no coma evident, the conclusion is it is a dead comet.”

2015 TB145 presents a rare opportunity to study a potentially hazardous object up close. By knowing what it is made of, we can plan for future encounters with asteroids that pose a real threat.

The project is funded by NASA Near-Earth Object Observations program. 

Visit to see a short video of the asteroid prepared using Arecibo Observatory radar images. Credit NAIC-Arecibo/NSF.

Asteroid 2015 TB145 will safely fly by our planet on Halloween at 1:01 p.m. EDT (10:01 a.m. PDT).

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