Earth's Second Moon, 3753 CruithneEveryone knows and loves the moon. What you may not know is that it's not Earth's only natural satellite. In 1997, another body was discovered, 3753 Cruithne, also called a quasi-orbital satellite of Earth. This means that Cruithne doesn't orbit Earth in a nice ellipse the same way our moon does. Instead, Cruithne scuttles around the inner solar system in what's called a horseshoe orbit.
The video illustrates what a horseshoe orbit looks like, specifically for Cruithne orbiting around Earth. This is something not widely known, but this type of orbit is actually pretty common in our solar system. Cruithne's orbit is so wide, that its sometimes goes into the neighborhood of Venus and Mars. It orbits the sun about once a year, but it takes nearly 800 years to complete this messy ring shape around Earth's orbit.
Even though Cruithne could technically be considered Earth's second moon, there isn't too much information about what it's like on surface. It's only approximately five kilometers across, the surface gravity is very weak. Walking briskly is probably enough to send you strolling out into outer space.
Even though Cruithne is small, if it were to strike Earth, it would be an extinction-level event, similar to what is believed to have happened at the end of the Cretaceous period. However, it's not going to hit us any time soon. It's orbit is tilted out of the plane of the solar system, and astrophysicists have provided simulations confirming that it will not come anywhere near us anytime soon.
Posted in: Science