Near-Earth Asteroid 3753 Cruithne

Near-Earth asteroid 3753 Cruithne

The relative motions of 3753 Cruithne and the Earth are shown. After a few orbits, the lines of sight connecting Cruithne to the Earth are drawn in green. Note that, though they both go around the Sun, both are always on the same side of the Sun. Then, the Earth will begin "picking up" the lines of sight, constructing the apparent path of Cruithne as seen from the rotating Earth. Their motions are such that Cruithne appears to perform a kidney-shaped loop around the Earth. Though the asteroid thus appears to orbit the Earth, this is a result of the frame of reference we are using. Also note that the presence of the Earth at the centre of the kidney is simply a result of their mutual synchronization: the Earth is lined up with the asteroid and Sun when the asteroid is at perihelion (its closest approach to the Sun). If the Earth and asteroid are synchronized differently, the asteroid will continue to perform a kidney-shaped loop every year, but the loop will not be centred on the Earth. For example, if the Earth is 180 degrees away from Cruithne when the asteroid reaches perihelion, the kidney bean will also be 180 degrees (ie. on the other side of the Sun) from our planet.

More info here:
http://www.astro.uwo.ca/~wiegert/3753/3753.html

Category:

Science & Technology

Tags:

• Near-Earth
• asteroid
• 3753
• Cruithne
• orbit