Newton’s eeerrr…. first law – every keeps doing what its already doing unless something stops it. That’s not obvious here on earth itself, because if you spin something here there are things to stop it … usually friction. There’s nothing much out in space for the earth to rub against to create friction.
The earth is slowing down a very little bit (someone asked about the moon in todays chat – and as the moon goes around us some of the earth’s spin energy gets shared out with the moon by the gravity that holds the earth-moon together). Some of the earth’s energy goes in dragging weather around… there’s a bit of friction between the atmosphere and the earth but the earth is so much more massive than the atmosphere that its a minute effect.
Other things happen too – the Japanese earthquake was so big it made the whole earth jump. Japan actually moved a few metres, and the earth’s spin shifted a bit.
Nice question and nice answer from Chris! The Earth is spinning as a result of left over kinetic energy (movement) from when it formed.
The Earth formed from a disk of dust, gas, rock etc. some of which went to form the other planets, some to the Earth and most(?) to the sun. That disk of dust was orbiting around the sun and as it formed into planets, that kinetic energy was transferred into making the Earth orbit the sun and making it rotate about its axis.
Correct me if I’m wrong Chris.