An asteroid that could be as big as the Chrysler Building is expected to fly past Earth safely this weekend.
The space rock, known as 2013 CU83, is expected to come closer to our planet. According to figures from NASA’s Center for Near Earth Studies database, the asteroid will be about 4.3 million kilometers from Earth at 11:37 p.m. UTC, or 7:37 p.m. ET, on Saturday.
To put this close approach into context, 4.3 million miles is roughly 18 times the average distance between Earth and the Moon. While that may seem like a long distance, on the scale of the solar system, astronomers consider it a close approach. But the trajectory of this object is well known and there is no chance that 2013 CU83 will collide with our planet this time.
Asteroids are rocky objects that orbit the sun much like planets, although they are much smaller.
These space rocks vary greatly in size. The largest known asteroid is Vesta, which measures about 329 miles in diameter. But most asteroids are much smaller, with some measuring less than 33 feet in diameter.
To date, more than 1.1 million asteroids have been identified, according to NASA, most of which are found in the main asteroid belt located between the orbits of Mars and Jupiter.
As it closes in on Earth, the 2013 CU83 will travel at speeds of approximately 13,100 miles per hour, which is more than six times faster than a rifle bullet, or seventeen times faster than the speed of sound, according to CNEOS figures.
The size of the asteroid is estimated to be between 459 feet and 1,050 feet in diameter based on its observed magnitude in the sky. At the upper end of that size range, the 2013 CU83 would be about as tall as the Chrysler Building in New York.
Estimating the size of asteroids can be difficult for astronomers, which is why the CNEOS provides a range.
“Measuring the size of distant objects in space is difficult,” said Greg Brown, an astronomer at the Royal Observatory in Greenwich in the UK. Newsweek in May. “Because often we are not able to physically see its size – they often show up as unresolved dots in telescopes – astronomers often have to determine its size based on its brightness.”
“The bigger it is, the more light it will reflect and therefore the brighter it will appear,” he said. “However, this requires an assumption about the degree of reflectance of the material it is made from, which can vary widely. Add a number of other complications and the actual size of an object can be very different from the calculated value. .”
2013 CU83 is one of more than 29,000 near-Earth objects, or NEOs, that scientists have discovered so far, the majority of which are asteroids. The term is used to refer to any astronomical body that passes within approximately 30 million kilometers of our planet’s orbit.