A day on Venus lasts about 243 days. More specifically, this is the time it takes Venus to complete one rotation on its axis. This type of day is called a sidereal day. A solar day is the time it takes the Sun to return to the same spot in the sky. For Venus this takes roughly 117 days. You can think of a solar day as the day/night cycle. For Earth, a sidereal day is about 4 minutes shorter than a solar day.