46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years. The comet was discovered photographically on January 17, 1948, by the American astronomer Carl Avatar Wirtanen.

On 16 December 2018 the comet passed 0.0774 AU from Earth, reaching an estimated magnitude of 4.2, making this pass the brightest one predicted, and the brightest close approach for the next 20 years.