A planet's day is the time it takes the planet to rotate or spin once on its axis. Venus rotates much more slowly than Earth does, so a day on Venus is much longer than a day on Earth. A day on Venus lasts for 243 Earth days or 5,832 hours!A day on Earth is 23.943 hours.Venus also rotates backwards compared to the Earth and most of the other planets.enus rotates much more slowly than Earth does, so a day on Venus is much longer than a day on Earth. A day on Venus lasts for 243 Earth days or 5,832 hours! A day on Earth is 23.943 hours.