A large dead comet that eerily resembled a human skull has safely skimmed past the planet on 1 p.m. EDT (10 a.m. PDT, 17:00 UTC) this Halloween.
Scientists said the dead comet, which was first thought to be an asteroid, had missed Earth by about 302,000 miles (486,000 kilometers), a distance that is just 1.3 times farther than the moon. Named asteroid 2015 TB145, the dead comet once churned out volatiles or debris around the sun.
NASA has been observing the asteroid through the Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Data from the Arecibo Observatory in Puerto Rico suggests that the spherical space object is more than 2,000 feet (600 meters) in diameter, and rotates on itself every five hours with a speed of 22 miles per second (35 kilometers per second).
"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 IRTF program scientist Kelly Fast.
Vishnu Reddy, a researcher from the Planetary Science Institute in Arizona, described the object to be similar to fresh asphalt. He said that it reflects six percent of the sunlight it receives, and that while it may seem pretty dark but it is actually brighter than a typical comet.
It could be cometary in origin, but because there is no coma evident, scientists concluded it was a dead comet.
Fortunately, the space object, also known as "The Great Pumpkin", safely cruised by the planet without causing any harm.
In addition to recording scientific data, experts said tracking the space object could help develop counter-measures against asteroids that may go on a collision course with the planet.
Astrophysicist Gianluca Masi featured a live stream through the Virtual Telescope to track the asteroid.
"I always like looking at those close approaches," said Masi. "They (show that) we do live in such dynamic solar system, where collisions play such a big role in shaping planets, Earth included."
Asteroid "visits" in the ancient times once had great impact on the planet, Masi added. Now, scientists are closely studying the physical properties of these space objects.
Meanwhile, NASA predicted that asteroid 2015 TB145 will likely come back to the Earth's neighborhood on September 2018, and will pass by at about 24 million miles (38 million kilometers) away from the planet.
