WARNING: Extremely off-topic!
So recently I was thinking about Superman and some details about his powers. We know he can go back in time, but how? And could Superman save his planet, Krypton?
In Superman: The Movie (1978) Superman goes back in time approximately five minutes to save Lois Lane by turning around the Earth counter-clockwise approximately 150 times. Using this information, we can tell that Superman has to make .5 of a full rotation to go back in time one second.
So, how far away is Krypton anyway? Well, in recent times a star was singled out to be the real-life representation of Krypton’s star. This particular star is 21 light years away from Earth.
Now we have to figure out how long it would take Superman to reach his planet. Superman took approximately 2.5 years to get to Earth when he was a baby – either by opening a wormhole or by using some other means of faster-than-light travel. But Superman is not equipped with a spaceship in this scenario, he has only his flying powers. It is stated by Batman in one of his comics that Superman’s maximum speed is 10,563,300,000 mph, which is roughly translated to 283,000 meters per second. Using this speed, Superman would take around 2,648.338 years to reach Krypton.
Superman must now turn around the Earth enough times to compensate for the time it takes to reach Krypton. He would need to rotate a total of 41,953,832,853.59 times. This would take him 212.85 years, so he must also compensate for this and rotate 89,040,000 more times, which would take 1.412 years.
In conclusion, assuming that Superman can maintain the same speed to Krypton and all goes well, Superman would have around 1.088 years to prevent or somehow help the victims of the explosion.