Earth Has a Second Moon, Astronomers Say

In a research paper called "The population of natural Earth satellites", astronomers say that Earth has a second moon at any given time. While these moons are small, the scientific implications of this discovery are phenomenal.

Think about it: instead of having to send crews to asteroids, now we know that they come to us—they orbit Earth and we can intercept them to learn more about the origins of our solar system. All with a small price tag.

Interesting, however how do they know it wasn't an ET craft?