Besides minor planets, he has also discovered 3 comets. The parabolic comet C/1944 H1 observed in 1944 and 1945, as well as the two short period comets, 40P/Väisälä, a Jupiter-family comet, and C/1942 EA, a Halley-type and near-Earth comet. Together with Liisi Oterma he co-discovered the Jupiter-family comet 139P/Väisälä–Oterma, which was first classified as asteroid and received the provisional designation "1939 TN".
Besides minor planets, he has also discovered 3 comets The parabolic comet C/1944 H1 observed in 1944 and 1945, as well as the two short period comets 40P/Väisälä, a Jupiter-family comet, and C/1942 EA a Halley-type and near-Earth comet. Together with Liisi Oterma he co-discovered the Jupiter-family comet 139P/Väisälä–Oterma, which was first classified as asteroid and received the provisional designation "1939 TN".