A “possibly hazardous” near-Earth asteroid will pass by our planet tomorrow, followed by a larger one the following week — but don’t worry, Earth isn’t popular enough for either of these passing space rocks to impact us. According to NASA, asteroid 418135 (2008 AG33) will pass by at a speed of roughly 37,400 kilometers per hour (23,300 miles per hour), or about 30 times the speed of sound, on Thursday, April 28. It will pass within 3.2 million kilometers (2 million miles) of Earth, which is extraordinarily near in cosmic terms but around eight times the distance between us and the Moon.
The asteroid was initially detected in 2008, and it orbits the Earth every seven years. It was last seen on March 1, 2015, and it will return on May 25, 2029. It’s thought to measure between 350 and 780 meters (1,150 and 2,560 feet) broad, which is around twice the height of the Empire State Building, six Taj Mahals stacked on top of each other, or 144 giraffes on the bigger end. We’ve been known to use ferrets as a measuring unit, thus that’s 2,000 ferrets across (end to end).
However, it isn’t anywhere close to becoming the biggest space rock to sail past Earth this year. 467460 (2006 JF42) is scheduled to fly over on May 9 at a speed of 40,700 km/h (25,300 mph). The space rock is estimated to measure between 380 and 860 meters (1,247 and 2,822 feet) broad, dwarfing the world’s tallest structure, the Burj Khalifa. It will return to Earth on May 11, 2023, and is now anticipated to pass within 1.1 million kilometers (686,013 miles) of our planet on May 4, 2159.
The NASA Center for Near-Earth Studies (CNEOS) keeps a watchful check on any space objects that could come near to Earth. They’re called “potentially dangerous” because, while the chances of their colliding with us are remote, they’re in orbits that might change over millennia to eventually intersect Earth’s orbit. Tracking these space pebbles allows us to not only keep a watch on those that approach Earth too closely, but also to learn more about how asteroid orbits change. CNEOS detects any near-Earth objects (NEOs) orbiting the Sun that come within 48 million kilometers (30 million miles) of Earth’s orbit and are large enough to do severe harm on Earth (30-50 meters/98-164 ft).
What if someone got too close? Various initiatives and missions deal with the subject — but not in the sense that Don’t Look Up or Moonfall do. As part of the bi-annual Planetary Defense Conference, international governments and space organizations participate in a tabletop simulation on how to cope with oncoming space rocks. To be fair, Earth hasn’t had much luck deflecting the asteroid thus far, with big swaths of Europe obliterated and New York City in ruins.
Perhaps NASA’s first planetary defense mission, which will smash into an asteroid and knock it off track before it can reach us, will be more successful. The DART mission was launched in November of last year, and we’ll find out if it works when it gets at its target, the asteroid Dimorphos, in September of this year. China just declared that it will launch its own asteroid-smashing mission in 2025. To be clear, there are presently no known objects with trajectories that would take Earth out, but it’s always a good idea to be prepared. “Planetary defense” is defined by NASA as “identifying asteroids before they find us.”