Wirtanen discovered periodic comet 46P/Wirtanen, as well as eight asteroids, including notably the Apollo asteroid (29075) 1950 DA, which may have a non-negligible probability of impacting the Earth in the year 2880.
Objevil periodickou kometu 46P/Wirtanen a také osm planetek, včetně planetky Apollonovy skupiny (29075) 1950 DA, která může mít nezanedbatelnou pravděpodobnost dopadu na Zemi v roce 2880.