The Babylonians created an even more sophisticated Calendar than the Egyptians, the Mayans, and the Chinese. They studied the motions of the sun and the moon and designated the beginning of each month the day after the new moon. At first, this was determined by simply observing the sky, but later the Bablyonians were able to calculate it in advance. In 400 BC the Bablyonians realized that the speed of the motions of the sun and mon were not constant and that they moved with increasing speed for half of each revolution to a maximum speed and then to decrease to another speed for the second half. The Bablyonians were able to calculate the planetary positions and the motions they made. Archaeologists have found hundreds of tablets showing these calculations. Through these, the Bablyonians were able to predict the daily motions of the moon, the sun, and the planets every day of the year.