When a big asteroid passed by Earth last month, NASA scientists took what are described as far more detailed radar images of that kind of rock than have ever been taken before.
And the images of asteroid Toutatis on Monday are teaching scientists new things about the kind of object that may have killed the dinosaurs and eventually might make humans extinct.The images are "100 times more detailed than any previous picture of a near-Earth asteroid," astronomer Steven Ostro, of the space agency's Jet Propulsion Laboratory, said Sunday.
Asteroids are big chunks of rock in space. Most are located in a belt between Mars and Jupiter, but near-Earth asteroids have orbits that bring them close to Earth.
"Every once in a while they collide with our planet," Ostro said. "They have played a role in the evolution of life on Earth" by causing mass extinctions.
The radar pictures show Tou-tatis comprises two big chunks of rock, probably held in contact by gravity, he said. One chunk has an average width of about 2.5 miles; the other is about 1.6 miles wide, he said.
Scientists had thought Toutatis was only 1 mile to 2 miles wide until they took pictures as it whizzed within 2.2 million miles of Earth.