The brightest comet of 2018 will streak past Earth right after the peak of the Geminid meteor shower. Comet 46P/Wirtanen will be closest to Earth on Dec. 16, according to EarthSky, and is currently the brightest comet in the sky. The comet will come within about 7 million miles of Earth, putting it among the 10 comets that have come closest to the planet since 1950, according to the University of Maryland’s astronomy department. Comet 46P/Wirtanen appears in the sky as it orbits the sun about every five years.