Asteroid 99942, a cosmic rock about the size of the Golden Gate Bridge, will sweep past Earth on March 21.
Scientists first saw the asteroid, appropriately nicknamed Apophis, after the Egyptian god of chaos, as it was in our cosmic neighborhood in 2004, Space.com reports.
According to the site, Apophis is just the type of space object that pedestrians would want to know about, because it’s huge (about half a mile to 1 mile in diameter, according to Live Science) and sometimes it gets uncomfortably close to Earth.
While Apophis will glide past Earth next month from a safe distance of 1.25 million miles (about 40 times the Earth-Moon distance), its return in April 2029 will be much, much closer. Space.com reports that the asteroid will skim so close to Earth on April 13, 2029 that it will pass through our planet’s realm of high-altitude satellites, which is a distance of about 19,800 miles, according to NASA.
It is an extremely rare occasion for a foreign object of such size to come near Earth.
“This (is) something that occurs about once every 1,000 years,” said Marina Brozović, a radar scientist at NASA’s Jet Propulsion Laboratory in California (via Space.com). “So it clearly arouses a lot of interest.”
NASA reports that Apophis will be visible to the naked eye when it returns in 2029, and spectators in the southern hemisphere, mainly Australia, will see the asteroid as a speck of light moving east to west across the night sky.
As the rock flies past Earth, it will travel at a dizzying speed of 76,980 miles per hour, Newsweek reports. For reference, that’s about 100 times faster than the speed of sound and about a third the speed at which a bolt of lightning travels.
No asteroids are known to pose a significant risk to Earth in the next 100 years, Live Science reports. According to the site, today’s biggest known threat is an asteroid called (410777) 2009 FD, which has less than a 0.2% chance of hitting Earth in 2185.
In the meantime, NASA is studying ways to deflect future asteroids that are on a collision course with Earth, Live Science reports. Scientists have talked about using a spacecraft’s gravity to slowly pull asteroids from dangerous trajectories to safer trajectories.