A large space rock that looked like a dead comet just zipped past Earth this Saturday, Halloween night, NASA said in a news release, noting that the object fittingly looked like a skull.
"Scientists observing asteroid 2015 TB145 with NASA's Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun," the release said.
The object made its closest point to Earth at around 1 p.m. Saturday where it was located at a distance of just 486,000 kilometres away from our planet. That allowed astronomers to get close-up photos of the celestial body.
"The first radar images of the dead comet were generated by the National Science Foundation's 305-metre Arecibo Observatory in Puerto Rico," NASA said. "The radar images from Arecibo indicate the object is spherical in shape and approximately 600 metres in diameter and completes a rotation about once every five hours."
"The IRTF data may indicate that the object might be a dead comet, but in the Arecibo images it appears to have donned a skull costume for its Halloween flyby," said Kelly Fast, programme scientist at NASA headquarters and acting program manager for NASA's NEO Observations Programme.
The extraterrestrial body is shaped like an odd circle with two darker spots, making it look like a skull complete with empty eye sockets.
The eye sockets, according to NASA senior space researcher Amy Mainzer, are most likely craters or pits sculpted over time by impacts or the melting of ices.
"Who would have thought that this would have come with its own costume?" she said.
Instead of being spooked, space scientists used the skull comet for their research.
Astronomers originally thought the object headed towards our planet was a large asteroid. On Friday, just a day before the object made its closest pass to Earth, they said after observations that the object appears like a dead comet that is as dark as a printer toner.
Vishnu Reddy, a research scientist at the Planetary Institute in Tuscon, explained that astronomers changed what they earlier thought of the extraterrestrial object after it was observed to be reflecting 6 percent of light from the sun.
"While here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light," Reddy said in a statement, as quoted by The Los Angeles Times.
"That suggests it could be cometary in origin—but as there is no coma evident, the conclusion is it is a dead comet," he added.
The dormant comet is also bigger than previously thought. It was earlier estimated to be about 1,300 feet in diameter, but it is, in fact, closer to 2,000 feet long.
At this size, the space rock is about the length of five-and-a-half football fields, according to The Los Angeles Times.
The approaching comet may be massive as it is, but space scientists think it has already shed much of its size, made up of volatile materials, after several turns around the sun.
