Which Apollo mission was the only one to launch at night?

Apollo 17 was the only Apollo mission to launch at night.

Its Saturn V lifted off from Kennedy Space Center at 12:33 a.m. Eastern Standard Time on December 7, 1972. The mission had originally been scheduled for the previous evening, but a launch-sequencer problem caused a delay of 2 hours 40 minutes, pushing liftoff past midnight and into darkness.

Apollo 17 was also the final crewed Saturn V launch and the last Apollo lunar-landing mission. Commander Gene Cernan and lunar-module pilot Harrison Schmitt landed in the Taurus–Littrow valley, while command-module pilot Ronald Evans orbited above. The early-morning launch drew roughly half a million spectators in the surrounding area.

A common mix-up is to treat any launch before sunrise as a night launch in the same sense. Apollo 17 is the canonical answer because it was the only Apollo mission whose actual Saturn V liftoff occurred at night. The mission’s landing site was chosen for both ancient highland material and evidence of possible volcanic activity, making it the program’s most scientifically ambitious expedition.