How long is night on Ganymede?

The night on Ganymede lasts approximately 3 days, 13 hours, and 30 minutes.

Ganymede, being the largest moon in our solar system, is tidally locked to Jupiter. This means that its rotation period is synchronized with its orbital period around the gas giant. Consequently, one side of Ganymede always faces Jupiter, and its "day"—the time it takes to complete one full rotation—is equivalent to its orbital period.

Understanding Ganymede's Day-Night Cycle

The total duration of a complete day-night cycle on Ganymede is seven days and three hours. This period represents the time it takes for the Sun to return to the same position in the sky, much like a solar day on Earth. Since a tidally locked body typically experiences an approximate equal distribution of daylight and darkness, the length of night is roughly half of this total cycle.

Here's a breakdown of the calculation:

• Total Day-Night Cycle: 7 days and 3 hours
• Convert to Hours:
  • 7 days × 24 hours/day = 168 hours
  • 168 hours + 3 hours = 171 hours
• Calculate Night Duration:
  • 171 hours / 2 = 85.5 hours
• Convert back to Days, Hours, and Minutes:
  • 85.5 hours ÷ 24 hours/day = 3 full days with a remainder.
  • 3 days × 24 hours/day = 72 hours
  • Remaining hours = 85.5 hours - 72 hours = 13.5 hours
  • 13.5 hours = 13 hours and 30 minutes

Therefore, the night on Ganymede spans a significant period, making for very long stretches of darkness.

Key Characteristics of Ganymede's Rotation

The tidally locked nature of Ganymede has several implications for its environment and the experience of a "day" or "night" on its surface:

• Synchronous Rotation: Ganymede completes one rotation on its axis in precisely the same amount of time it takes to orbit Jupiter. This is a common characteristic among many moons in our solar system, including Earth's Moon.
• Fixed Face to Jupiter: While Ganymede orbits Jupiter, one hemisphere consistently faces the planet, much like how one side of our Moon always faces Earth.
• Long Solar Day: Because of this synchronization, the solar day (the time from one sunrise to the next) on Ganymede is very long, directly corresponding to its orbital period.

Duration Summary

To summarize the periods on Ganymede:

This extended period of darkness would mean that any surface features not illuminated by Jupiter's reflected light would experience prolonged cold temperatures, consistent with Ganymede's immense distance from the Sun. For more information on tidally locked celestial bodies, you can refer to general astronomy resources that explain this phenomenon.