An asteroid is going to come pretty darn close to Earth on Friday – although as always, there’s no chance of it hitting us.
The asteroid is called 2018 CB, and it’s going to pass Earth on February 9 at a distance of about 64,000 kilometers (39,000 miles). That’s five times closer than the Moon, enough to label it as a potentially hazardous asteroid (PHA). You can watch it fly by online from 3pm EDT on Friday.
It’s estimated to be between 15 and 40 meters (50 and 130 feet) across. It was discovered fairly late, only being spotted by the NASA-funded Catalina Sky Survey (CSS) in Arizona on February 4.
2018 CB is an Apollo asteroid, which is a group of 8,000 near-Earth asteroids that orbit in the inner Solar System, and regularly cross Earth’s orbit. About 1,500 of them are classified as PHAs.
The orbit of this asteroid takes it about to about 1.68 AU from the Sun (1 AU, astronomical unit, is the distance from Earth to the Sun). That’s about the same distance from the Sun that Elon Musk’s Tesla Roadster, launched the other day, will reach.
"Although 2018 CB is quite small, it might well be larger than the asteroid that entered the atmosphere over Chelyabinsk, Russia, almost exactly five years ago, in 2013," said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement.
"Asteroids of this size do not often approach this close to our planet -- maybe only once or twice a year."
It follows on the heels of another asteroid, 2018 CC, which swung past Earth on Tuesday, February 6. That asteroid measured 15 to 30 meters (50 to 100 feet) across, and came within 184,000 kilometers (114,000 miles) of our planet.
PHAs are classified as objects that exceed 500 feet (140 meters) in size and come closer than 7.5 million kilometers (4.6 million miles) to Earth. Currently, there is no known asteroid – PHA or otherwise – on a collision course with Earth in the next few centuries at least. Phew.
Still, the close call of this asteroid is a reminder of the millions of space rocks out there in the Solar System – and we really need to get better at tracking them. One might have our name on it one day, so we’d better be ready.