The massive asteroid, named Asteroid 2012 LZ1, was actually twice as big as astronomers predicted, according to new radar images of the giant space rock.
Space.com reports that the giant asteroid sailed within 3.3 million miles of Earth on June 14th, its closest approach. That distance is about 14 times the distance between Earth and the moon, meaning that the oblong space rock posed no threat to colliding with Earth.
However, that flyby did allow astronomers at the Arecibo Observatory to train the planetary radar system, which is a huge radio telescope in Puerto Rico. In doing so, they discovered that 2012 LZ1’s size was vastly underestimated.
MSNBC reports that Mike Nolan, the observatory’s director of planetary radar sciences, stated in a news release on Friday that:
“The sensitivity of our radar has permitted us to measure this asteroid’s properties and determine that it will not impact the earth at least in the next 750 years.”
According to ZeeNews, Arecibo Observatory’s Ellen Howell stated:
“This object turned out to be quite a bit bigger than we expected, which shows how important radar observations can be, because we’re still learning a lot about the population of asteroids.”
MSNBC reports that the scary part about the approach of asteroid 2012 LZ1 is how late it was detected. The space rock was detected on June 10th at the Siding Spring Observatory in Australia, which was only 4 days before its closest approach. While there was zero risk of collision, astronomers were still worried by how late it was detected.
Another challenge for observers is how dark the asteroid appears to have been, which is why its previous size estimates were so off. Without precise observations of the asteroid’s shape, astronomers have to base their size estimates on how much the asteroid reflects light at a given distance.
From the radar observations made by the Arecibo Observatory, scientists were able to determine that the rock was only reflecting 2 to 4 percent of the light that struck its surface (meaning that the asteroid was at least as black as coal, if not darker).
View footage of the asteroid’s passing below: