This 3D interactive program (above) shows the orbits of two comets: P/2016 BA14 (PANSTARRS) (red orbit) and 252P/LINEAR (blue orbit). These two comets passed safely by the Earth in March 2016. Their orbits are so similar that may have fragmented from each other in the past.
Custom Orbit Viewer applet provided by Ron Baalke (JPL).
See related story.
Below is an animation showing the two comet flybys.