Nearly two decades ago, a near-Earth asteroid was discovered to have a moon and the binary system was given the name “Didymos”—Greek for “twin,” a loose description of the larger main body and the smaller orbiting moon, which became unofficially known as Didymos B.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/nasasfirstpl.jpg)
Source:
https://phys.org/news/2020-06-nasa-planetary-defense-mission.html