Because of this, Cruithne and Earth appear to "follow" each other in their paths around the Sun. This is why Cruithne is sometimes called "Earth's second moon". Earth has a second moon, of sorts, and could have many others, according to three astronomers who did calculations to describe orbital motions at. Don't get too attached, though. It's not sticking around. A tiny moon wizzes across the night sky. This is going to sound preposterous, but. The Minor Planet Centre has just announced that the Earth has been orbited by a second moon for the past three years or so. Moons are common in our solar system. In simple terms, a moon is a natural satellite caught in a planet's orbit. Based on that definition, a second moon—a. Earth's second moon will make a close approach to the planet next week before drifting off into space, never to be seen again. Earth's second 'moon' is set to leave the space around our planet for the last and final time. Known as SO, the object was temporarily. The Minor Planet Center has announced that Earth now has two moons. But don't bother running outside to check – this second satellite is. So Cruithne is our second moon. What's it like there? Well, we don't really know. It's only about five kilometers across, which is not. Scientists say the 'mini-moon' is probably just retro space junk from a rocket booster launched a half-century ago.