Earth tonight (May 25) – close enough that, with some preparation and a decent telescope, amateur astronomers may blot out the stars.
This is a very big asteroid moon-and-asteroid system, called 1999 KW4, is made up of two rocks. The big one is about 0.8 miles (1.3 kilometers) wide, according to NASA, and shaped like a spinning top. The smaller one is more elongated and stretches 0.35 miles (0.57 km) along its longest dimension.
Together, the asteroid and its minimoon wants to pass Earth at a strange, steep angle that NASA called them "the least accessible … for a spacecraft mission of any known binary near-earth asteroid . "
Related: Doomsday: 9 Real Ways Earth Could End
The two asteroids will pass closest to Earth at 7:05 pm EDT (1
Back on May 25, 2001, according to NASA, the asteroids passed 6.7% closer to Earth than they would this time, at a distance of 3,005,447 miles (4,836.798 km). Seventeen years from now, on May 25, 2036, the rocks will pass 55.2% closer to Earth, 1,443,511 miles (2,323,106 km) – again, posing no threat worth worrying about.
These big rocks have been frequent flyers in our planet's neighborhood for a long time. "
" 1999 KW4 approaches within 0.05 AU of Earth several times each century, "NASA's report on the object said. "This trend exists from at least [the year] 1600 [to] 2500." [Black Marble Images: Earth at Night]
"AU" refers to "astronomical units," a unit equal to the distance between Earth and the sun. Sun 0.05 AU is equal to one-twentieth the distance between Earth and Sun, or about 4,650,000 miles (7,480,000 km). 500 years old.
EarthSky reported that during the space rocks in the Southern Hemisphere, appearing as fast-moving shadows against stars in the constellation Puppis. The two asteroids will remain visible for several days, though, according to EarthSky. North American asteroid hunters may spot the objects near the constellation Hydra on the evening of May 27.
NASA said that its Planetary Defense Coordination Office wants to continue to monitor the asteroids.
Originally published on Live Science .