On Monday, January 7, the asteroid 2016 AZ8 flew just 4.5 million kilometers away from Earth. Specialists at the Arecibo Observatory in Puerto Rico recorded the approaching space rock, and using a radar, they found that the AZ8 has a moon.
According to the data obtained, the main element of the binary system is nearly spherical with a diameter of 430 meters, and its moon has a more elongated shape, similar to a 180-meter-long cigar.
Binary asteroids are not as rare as you might think. Studies show that about 15% of near-Earth asteroids have a moon. In the past they have struck Earth, forming double impact craters, like a crater in Jämtland, Sweden.
In the future, space agencies may need to deflect or destroy a binary asteroid approaching us, so the study of binary systems’ properties is important to protect the planet.