Scientists pinpoint just how fast Santa would have to travel tonight

Scientists say Santa would need to travel 89 million miles ( 144 million kilometres ) to visit every child on the planet.

That is the equivalent of flying his sleigh all the way from Earth to the sun in a single night .

In order to leave some time for delivering presents, this means he needs to travel at 5.1 million miles per hour ( 8.2 million kmph), or 0.8 per cent of the speed of light.

Einstein predicts that Santa would gain more mass as he gets faster, but as he nears the light, objects travelling with Santa 's sleigh will become compressed in size.

This is the same as the Dopler Effect , the strangest effect that.

The faster something is moving the more pronounced this effect becomes.

Rudolf ’s breakneck flight will create an extraordinarily strong Dopler effect.

Red-coloured light has a wavelength, the distance between one peak to the next, of 694.3 nanometres when its source is at rest.

Flying at 10 per cent of the speed of light, we would see this light shift radically in either direction.