Google+ SpaceTravelFoundation: 3753 Cruithne the second Moon of Earth ?

September 10, 2013

3753 Cruithne the second Moon of Earth ?

Dear followers,

In March of 2012, astronomers at +Cornell University published the result of a computer study, presenting that asteroids orbiting the sun might temporarily become natural satellites of Earth. They are called quasi-satellite. The most famous quasi-satellite is also called the second moon for Earth is 3753 Cruithne. This object is five kilometers wide ( 3 miles). 

Credits: 3753 Cruithne


A quasi-satellite is an object in a co-orbital configuration with a reference planet (for 3753 it's Earth). Scientists would say there is a 1:1 orbital resonance between Earth and this object. In other words, a quasi-satellite is orbiting the sun, like Earth. Its orbit around the sun takes exactly the revolution time as Earth’s orbit, but the shape is slightly different.

Astronomers discovered 3753 Cruithne in 1986, but it wasn't until 1997 that they figured out its complex orbit. It’s not a second moon for Earth; it doesn't orbit Earth. But 3753 Cruithne is co-orbiting the sun with Earth. Like all quasi-satellites, 3753 Cruithne orbits the sun once for every orbit of Earth.