skull shaped asteroid, asteroid, space rock,
This is an artist's illustration of the "Halloween Asteroid" 2015 TB145, which looks like a skull.J. A. PeƱas/SINC

The eerie space rock called 2015 TB145, also known as "Halloween asteroid", was first spotted by astronomers three years back. And it will pass by earth, once again, in 2018.

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The asteroid is 2,100 miles wide (640 metres), it had passed by Earth on October 31, 2015. The asteroid had come as close as 300,000 miles (480,000 kilometres) to Earth.

When the space rock was observed during its flyby with the help of various instruments and it was found to be skull-shaped from some angles. Even NASA captured this spooky asteroid using the Green Bank (West Virginia, USA) and Arecibo (Puerto Rico) radio telescopes, a website called agenciasinc.es reported.

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Appearing like a giant skull, the rotation period of this asteroid is 2.94 hours. The space rock reflects five to six percent of sunlight that hits it, astronomers found.

"This means that it is very dark, only slightly more reflective than charcoal," Pablo Santos-Sanz, an astrophysicist at the Institute of Astrophysics of Andalusia in Spain, was quoted as saying by space.com.

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Santos-Sanz has co-authored a study about the characteristics of this skull-shaped asteroid which was published in February 2017 in a journal Astronomy & Astrophysics.

This space rock is speculated to be an extinct comet which lost its water content and other materials while revolving around the Sun, the astronomers said. The asteroid completes its lap around the Sun in 3.04 years, the asteroid will pass by our planet next time in November 2018.

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The asteroid will pass by Earth at 105 Earth-moon distances.

"Although this approach shall not be so favorable, we will be able to obtain new data which could help improve our knowledge of this mass and other similar masses that come close to our planet," said Santos-Sanz as quoted in a statement.