Days on Earth are slowing, literally! The force of the Moon slows the rotating Earth. Every century, a day on Earth is 0.0016 seconds longer.
The Moon is tidally locked to the Earth. That is, as the moon orbits the Earth, only one side of it faces us. The dark side of the Moon refers to the side that is always facing away from us. Although we cannot see this side from Earth, the sun does shine on it.
The speed of light is approximately 300,000 kilometres per second. That is, light can travel around the world 7 and a half times in one second!