The asteroid that whizzed past Earth on Halloween appears to have taken off its costume. While originally captured by Puerto Rico's Arecibo Observatory looking a lot like a skull, NASA has captured new, high-resolution images that make the asteroid appear less menacing.
As the 2,000-foot wide space rock flew past Earth on Oct. 31 at 1 p.m. Eastern time, huge, Earth-bound radio telescopes in California and West Virginia bounced radar signals off the asteroid flying about 1.3 lunar distances (300,000 miles) away, capturing shots of asteroid 2015 TB145.
"The radar images ... reveal pronounced concavities, bright spots that might be boulders, and other complex features that could be ridges," said Lance Benner of NASA's Jet Propulsion Laboratory in Pasadena, California, who leads NASA's asteroid radar research program, in a statement. "The images look distinctly different from the Arecibo radar images obtained on Oct. 30 and are probably the result of seeing the asteroid from a different perspective in its three-hour rotation period."
As Space.com put it, the skull shape was likely "an optical illusion." The dead comet never posed any risk to Earth, but it is thought to be the closest approach by an asteroid expected until August 2027. Keep in mind, though, that this most recent close-call was only detected a few weeks before it zoomed by. Still, NASA says it "places a high priority on tracking asteroids and protecting our home planet," adding that the space agency has located about 98 percent of known Near Earth Objects.
To capture the asteroid in high-def glory, scientists used the 230-foot DSS-14 antenna at Goldstone, Calif., to beam high-power microwaves toward the asteroid. The signal bounced off the asteroid creating an echo that was then received by the National Radio Astronomy Observatory’s 330-foot Green Bank Telescope in West Virginia. The radar images created by this long-distance triangle provided a resolution clarity of 13 feet per pixel.
According to the space agency, radar is a useful tool in its arsenal for examining an asteroid's size, shape, rotation, surface features, and surface roughness, and for getting calculations of asteroid orbits just right.
The Halloween asteroid will swing by Earth again in September 2018, this time at a more comfortable distance of 24 million miles away.