Answer:
On Mercury, a day (the time it takes for the planet to complete one full rotation on its axis) is 59 Earth days long. Additionally, Mercury's orbit around the sun is much faster than Earth's, so its year (the time it takes to orbit the sun once) is only 88 Earth days long.
Since the astronauts are waiting for the next sunset at the same spot, they are essentially waiting for Mercury to complete one full rotation on its axis. So they will have to wait for one Mercury day, which is 59 Earth days long.
Since the year on Mercury is shorter than its day, the planet rotates on its axis three times for every two orbits around the sun. This means that there are approximately 1.5 Mercury days in each Mercury year.
Therefore, the astronauts will have to wait for approximately 39.3 Earth days (59 Earth days/Mercury day * 1.5 Mercury days/Mercury year) for the next sunset at the same spot.
Step-by-step explanation:
Mercury takes approximately 59 Earth days to complete one full rotation on its axis. This means that from one sunrise to the next, it takes approximately 59 Earth days. This is because a day on any planet is defined as the time it takes for the planet to make one full rotation on its axis.
Mercury takes approximately 88 Earth days to complete one orbit around the sun. This means that from one sunrise to the next, it takes approximately 88 Earth days. This is because a year on any planet is defined as the time it takes for the planet to make one full orbit around the sun.
However, since Mercury rotates on its axis three times for every two orbits around the sun, it means that it takes 1.5 Mercury days to complete one full orbit around the sun. This is because in the time it takes Mercury to orbit the sun once, it rotates on its axis three times.
So, if the astronauts wait for one Mercury day (i.e. one full rotation of the planet on its axis), they will have to wait for approximately 59 Earth days.
But since it takes 1.5 Mercury days to complete one orbit around the sun, the planet will have to rotate approximately 1.5 times before the same spot faces the sun again. This means that the astronauts will have to wait for approximately 1.5 Mercury days or 1.5 x 59 Earth days = 88.5 Earth days for the same spot to face the sun again.
Therefore, the astronauts will have to wait for approximately 88.5 Earth days - 59 Earth days (for one Mercury day) = 29.5 Earth days for the next sunset at the same spot. Rounding up, this is approximately 39.3 Earth days.