A green comet will appear in the night sky for the first time in 50,000 years. NASA scientists said the comet is expected to make its closest approach to the sun, or perihelion, on Jan. 12, and will be visible to stargazers in the Northern Hemisphere. Those in the Southern Hemisphere should be able to view the comet in February. The comet will shift to the northwest on the horizon throughout January and it will make its closest pass of Earth between Feb. 1 and Feb. 2, according to NASA. During that time, the comet will be 26 million miles away from the planet, according to astronomers.