Year of the Comet
Comet C/2011 L4 (PANSTARRS)

PANSTARRS information

Comet C/2012 S1 (ISON)

ISON information

Ask Astro

Published: June 1, 2006
It is possible for two objects to share the same orbits, but not the exact same orbit. Saturn's moons Janus and Epimetheus run on orbits that differ in size by only 30 miles (50 km). This similarity results in a surprising interaction: The two moons swap orbits every 4 years.
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