Superman Would Have To Fly This Fast To Reverse The Earth's Spin

At the end of Superman: The Movie, the Man of Steel flew around the world fast enough to reverse the spin of the planet, reversing time and allowing him to save the life of Lois Lane, who had died in the previous scene.

Of course, in reality if he were to do that, it would likely have catastrophic environmental consequences, and rather than turning back time, it would simply damage the hell out of the planet.

Is it even possible? Nerdist reports that, theoretically, yes, but it would be a virtual act of God. Here:

Through their calculations, the University of Leicester team concluded that Kal-El would have had to fly at an angular velocity of 46.296 radians per second, or 660,000,000 miles per hour — 98% the speed of light (!) — to reverse the spin of the Pale Blue Dot. But that's not all: compared to the Earth, Superman is a very small blob. In order to have a measurable effect on the massive celestial body then, he would also have to increase his own mass 13.7 million times over.

That's theoretically not impossible, although it would take Superman-level abilities to do so.

"Rest mass doesn't change, as it is independent of speed by definition," said Caltech applied mathematician Dr. Spyridon Michalakis. "Still, there is another 'mass,' known as 'relativistic mass,' which refers to the mass of an object that is moving very, very fast."

This is a concept that's been used in The Flash a few times in the comics, although the mass thing not yet on the TV series. Such an action could also prove problematic because in order to make it work, he would have to increase his mass to such a point that it could pull near-Earth objects like meteors out of their orbits.

There's a better way to time-travel, Clark. Maybe have a little chat with Rip Hunter?