# Here's How Fast Superman Would Have to Fly Around the Earth to Reverse Its Spin

Monday, 07 December 2015 - 12:34PM
Monday, 07 December 2015 - 12:34PM
In the 1978 Superman film, Superman travels back in time by flying around the Earth at such high speeds that he reverses the spin of the planet. But how fast would he actually have to travel in order to save Lois Lane? A team of students from the University of Leicester actually calculated the required speed in a new paper, and it turns out that, shockingly enough, it probably couldn't have happened exactly the way it happened on screen.

To reverse the planet's spin, Superman travels at an opposite direction to the Earth's movement and transfers his inertia, causing the Earth to mimic his direction. From general relativity, we know that an object moving close to the speed of light becomes more massive, and inertia is directly proportional to mass. So in order to reverse the Earth's spin, he would need to increase his mass by 13.7 million times. As a result, he would need to be traveling at near-relativistic speeds: 660 million miles per hour, or 98% the speed of light. Alternatively, he could fly around the Earth much longer than 50 seconds, as is shown in the film.

If he did attempt to change the Earth's spin, there would be extremely heavy winds as a result, and there would be pressure changes as well. As a result, relatively small near-Earth objects would be pulled towards the Earth, such as asteroids (although they assure us that the moon would be in no danger of falling).

In conclusion, Superman's act would not only have set near Earth objects, such as asteroids that happen to be near close to Earth due to their orbit around the sun, on a course for Earth but the changes in atmospheric pressure and wind speed due the wind speed still travelling at the speed before rotation change (twice the angular velocity of Earth) will most likely cause extinction. So spread the word: Do not try this at home.

Via Blastr.