Sunita Williams and Butch Wilmore’s return to Earth were delayed due to delays in the Boeing Starliner spacecraft’s return schedule, keeping her in orbit until February 2025. Their stay was extended to around eight months after NASA deemed it “too risky” to bring them back on Starliner. Sunita Williams and Butch Wilmore will continue their ISS works and are expected to return to Earth in February next year.
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How Sunita Williams sees 16 sunrises, sunsets a day
The International Space Station completes a full orbit around the Earth at a speed approximately 28,000 km/h, which is 17,500 miles per hour, every 90 minutes. This means astronauts see a sunrise or sunset every 45 minutes. Astronauts aboard the ISS experience 16 day-night cycles in a single Earth day.
As the space station travels, it moves from the bright side of Earth into the shadow and then back to the side of sunlight. And everytime this happens, astronauts experience a new sunset or sunrise. And so, in just one Earth day, they witness the sunrise and sunset 16 times. Sunita Williams called the view “beautiful” and “surreal”.ALSO READ: Sunken cheeks, heavy weight loss: Sunita Williams’ latest photos raise serious health concerns
How space’s day and night cycle works
On Earth, the day and night cycle is caused by the rotation of the planet. It takes approximately 24 hours for Earth to complete one full rotation, which presents us with a consistent tempo of daylight and darkness. However, the ISS orbits Earth significantly faster than Earth rotates. As the ISS moves in its orbit, astronauts face sunlight for 45 minutes, and then 45 minutes of darkness. This cycle repeats itself 16 times every 24 hours.
How to keep track of time in space
Astronauts use very accurate atomic clocks to stay connected with their teams on Earth and keep things running smoothly. These clocks are important for navigation and communicating with Earth.
They follow a schedule based on Coordinated Universal Time (UTC) because there are no regular day-night cycles in space. Their days are divided into roughly 5-minute periods for work, exercise, food, and rest, a schedule they stick to rigidly in order to maintain both mental and physical health in space.
On Earth, the rising and setting sun helps us know when to sleep and wake up. But in space, astronauts on the ISS don’t have that. The station moves so fast that it’s always switching between light and dark, which can mess with their sleep. To manage, they follow a strict schedule based on UTC to make sure they get enough rest and stay healthy.