To calculate the total time that has passed on Earth, we need to add up the time it took for the spacecraft to travel to the planet, the time it spent there, and the time it took to return to Earth.
Traveling to the planet: The spacecraft traveled 20 light-years in 803 years. Since the speed of light is the maximum speed in the universe, we can assume that the spacecraft traveled at the speed of light. Therefore, the time experienced on Earth would be the same as the time experienced on the spacecraft during this journey, which is 803 years.
Time spent on the planet: The spacecraft remained on the planet for 220 years. Since the spacecraft was stationary relative to the planet, time passed on Earth at the same rate. Therefore, 220 years passed on Earth during this period.
Returning to Earth: The spacecraft traveled back from the planet to Earth, a distance of 20 light-years, in 238 years. Again, assuming the spacecraft traveled at the speed of light, the time experienced on Earth would be the same as the time experienced on the spacecraft during this journey, which is 238 years.
Adding up the three periods: 803 years + 220 years + 238 years = 1261 years
Therefore, a total of 1261 years have passed on Earth.