Comet Lulin, a rare green comet discovered in 2007, is set to make its closest approach to the Earth around Feb. 24. The comet's green color comes from the gases that make up its atmosphere. Its closest approach to Earth will be 38 million miles. James Sowell, principal academic professional in the School of Physics and director of the Georgia Tech Observatory, joins Atlanta News First to talk about the best times to view the comet, where it may have originated, and how rare green comets are in the universe.