The comet 46P/Wirtanen, which passes Earth every 5.4 years, was one of three comets discovered by Carl Wirtanen in 1948 at the Lick Observatory in California. This orbit will be one of the closest comet orbits to Earth since the 1950s, according to Space.com. The comet 46P will likely not have a large observable tail because of its relatively small size, according to Space.com. It measures 0.68 miles in diameter, one-tenth the size of the popular Halley's Comet. Currently, 46P is a small blueish object in the night sky. The comet will be passing in the Southern sky, near the...