The length of one earth day is approximately 24 hours (actually 23'56). Which planet in our solar system has the longest day, equivalent to about 244 earth days?

Our home planet completes a full rotation, defining one day, in approximately 23 hours and 56 minutes, which we commonly round to 24 hours. This spin on its axis is what gives us our cycle of day and night. However, not all planets spin at the same rate, leading to vastly different day lengths across our solar system.

Among our celestial neighbors (Review), one planet stands out for its remarkably sluggish rotation: Venus. A single day on Venus stretches out for an astonishing period, taking about 243 Earth days to complete just one full turn on its axis. This makes a Venusian day longer than its year, as Venus orbits the Sun in approximately 225 Earth days. This extremely slow rotation, combined with its retrograde motion (spinning in the opposite direction to most other planets), contributes to its unique and extreme environment.

The leisurely pace of Venus's rotation has profound effects on its surface and atmosphere. Without a rapid spin, there's less Coriolis effect, which on Earth influences weather patterns and ocean currents. The thick, toxic atmosphere of Venus, composed primarily of carbon dioxide, traps heat through a runaway greenhouse effect, making it the hottest planet in our solar system. The incredibly long periods of daylight and nighttime on different parts of the planet further contribute to the extreme conditions found on its surface, where temperatures are hot enough to melt lead.