Produced by: Mohsin Shaikh
Astronauts on the ISS experience 16 sunrises and sunsets daily. NASA astronaut Sunita Williams describes this surreal view as a “privilege” earned from her hard work and dedication to space exploration.
The ISS orbits Earth at 28,000 km/h, completing a full orbit every 90 minutes. This speed brings astronauts from daylight to darkness roughly every 45 minutes, creating an intense day-night cycle.
Unlike Earth’s steady 12-hour cycles, ISS astronauts endure a fast-paced rhythm: 45 minutes of light, followed by 45 minutes of dark, 16 times per day, offering a unique “time warp” effect.
Williams’ current mission was extended due to delays in the Boeing Starliner return schedule, keeping her in orbit until February 2025. She’s using the extra time for research and exploration alongside astronaut Butch Wilmore.
In 2013, Williams recalled her experience to students at the University of Gujarat. She described witnessing multiple sunrises and sunsets as one of the wonders of space travel—an experience she eagerly shares.
The rapid day-night cycle is due to the ISS’s orbit speed, which carries astronauts from Earth’s dark to sunlit side every 90 minutes. This swift orbit ensures they see frequent sunrises and sunsets.
Unlike Earth’s natural cycle, astronauts’ day-to-day lives are structured by Coordinated Universal Time (UTC), as there’s no true sunrise or sunset to guide their schedules in space.
Astronauts rely on atomic clocks for precise timing, essential for navigation, especially beyond Earth. These clocks keep the ISS crew synchronized with teams on the ground.
Life on the ISS is meticulously organized in five-minute intervals for work, meals, and rest, ensuring astronauts stay physically and mentally aligned amid their 90-minute day-night rhythm.