Curious asteroid Selam, spotted by NASA's Lucy spacecraft, is a cosmic toddler

Three grey space rocks in the blackness of space. the largest is alone on the left; the smaller two are on the right, touching one another.

When NASA's Lucy mission passed by the near-Earth asteroid Dinkinesh last November, it discovered that Dinkinesh had a companion — a little moonlet that astronomers soon named Selam. And now, scientists have measured Selam's age. Their estimate suggests that tiny Selam separated from its larger partner Dinkinesh just 2 to 3 million years ago, making Selam a toddler — by solar system standards, of course.

"Finding the ages of asteroids is important to understanding them, and this one is remarkably young when compared to the age of the solar system, meaning it formed somewhat recently," Colby Merrill, a doctoral student at Cornell University, said in a statement.