In a rare stroke of celestial coincidence, two lumpy asteroids – one that could destroy a city, the other big enough to wipe out the planet – are zooming by Earth, close enough to excite observers but posing zero risk of hitting us. Asteroids in our neighborhood always ignite interest, but these two are special because of their timing, size, and orbits. Their separate-path visits came 42 hours apart and, in yet another fluke, just ahead of this year’s Asteroid Day. That’s the annual observance of the Russian Tunguska meteor event in 1908, the largest asteroid impact in modern history.
Though their orbits are considered close to us in astronomical terms, neither was visible to the unaided eye. One of them has already come and gone: Asteroid (415029) 2011 UL21, a chunk of rock the size of Mount Everest, passed closest to Earth without incident on Thursday. The second, asteroid 2024 MK, will arrive Saturday morning. Though it’s much smaller than its companion, at 400 to 850 feet long, 2024 MK will come much closer to Earth. It’ll pass between us and the moon at a distance of about 180,200 miles. The moon is 238,900 miles from Earth. Though larger, 2011 UL21 came no closer than 4.1 million miles to us.
2024 MK is about the size of Dimorphos, an asteroid NASA used in its first-ever successful planetary defense test about two years ago. The space agency crashed a 1,260-pound NASA spacecraft into Dimorphos, 7 million miles away, and altered its orbit by 32 minutes. You may be able to see the asteroid sometime Saturday with a telescope or a pair of strong binoculars, Smithsonian Magazine says. Those in Hawaii and South America have the best viewing opportunities. It might also be seen from the southern continental U.S. The asteroid’s closest approach was at 9:46 a.m. Eastern time. It may be possible to see it Saturday night after the sun sets.
The Asteroid Watch dashboard tracks asteroids and comets that will make relatively close approaches to Earth. The dashboard displays the date of closest approach, approximate object diameter, relative size, and distance from Earth for each encounter. The object’s name is displayed by hovering over its encounter date. Clicking on the encounter date will display a Web page with details about that object. The dashboard displays the next five Earth approaches to within 4.6 million miles (7.5 million kilometers or 19.5 times the distance to the moon); an object larger than about 150 meters that can approach the Earth to within this distance is termed a potentially hazardous object. The average distance between Earth and the moon is about 239,000 miles (385,000 kilometers).
Source: USA TODAY Network reporting and research; NASA; European Space Agency; earthsky.org; asteroidday.org; space.com; Reuters; sciencealert.com
