Earth has a close encounter this morning when Asteroid 2019 OK at 1:22 GMT, at a speed of nearly 55,000 miles (88,500 kilometers) per hour. 45,000 miles (72,500 km), a safe distance, but still much less than the distance between the Earth and Moon.
Astronomers only noticed the space rock within the past few days, when astronomers at SONEAR Observatory in Brazil picked it up. Because it's such a newcomer, there's a lot of astronomers are not sure about, from its orbit to its size, which ranges from 187 to 426 feet (57 to 130 meters) across.
Close-up of the Earth , those space, where you can come back remotely close to our planet's orbit. NASA considers it its main avenue of planetary defense, and has at least 90 percent of NEOs 460 feet (1
For reference, the asteroid purported to have killed the dinosaurs 66 million years ago was about 10 miles (16 km) across from Chelyabinsk, Russia in 2013 was only 66 feet (20 m) across.
So if 2019 OK had struck Earth, it could have delivered quite the blow to any city it struck, but would not have been a world-wide event. Hiroshima.
But the real effects are unclear, because there's still uncertainty about how big the asteroid was. The large range, between 187 and 426 feet (57 to 130 m), occurs because astronomers can only measure how bright the object is.
Often, NASA and other observatories spot asteroids the size of 2019 OK when they're much farther from Earth, giving more time to understand and, if necessary, prepare for a meteor strike.
Just as baseball players have trouble spotting balls when the sun is in their eyes, so too do telescopes have a harder time tracking small objects when they're closer to the Sun.
It's possible other objects also sneak by Earth under cover of light. But the bigger the asteroid, the harder it is to hide, and NASA is keeping eyes open.