Description
Transcript: We always see the same features on the surface of the Moon. This means that the Moon's rotational period equals the time that it takes to orbit the Earth. This is called synchronous rotation. The time that it takes for one phase of the Moon to recur in the night sky is called the Moon Synodic period. It's twenty-nine and a half days. This is different from the Moon's sidereal period which is the time that it takes for a fixed phase of the Moon to reappear amongst the fixed stars; this is only 27.3 days. The phases of the Moon are one of the most prominent patterns in the night sky. They have been known to civilizations and fairly accurately measured for tens of thousands of years.
Transcript: In the year 584 B.C., on the coast of Asia Minor, two warlike tribes were engaged in a fierce battle: the Medes and the Lydains. As written by the Greek poets, these two cultures were hacking away at each other on the battlefield with burnished swords and shields, when suddenly the...
Published 07/12/11
Transcript: Thales was a philosopher who lived in the 6th century B.C. in Miletus, in what is now Turkey. No written work by Thales survives, but we know that he kept accurate eclipse records and he speculated about astronomy. He decided that the source of all things was one thing, and that...
Published 07/12/11
Transcript: The apparent motions of the stars in the night sky depend on your position on the Earth’s surface. At a northern temperate latitude, the stars rise in the east and set in the west, and they travel on slanting paths across the sky. The north celestial pole sits in the northern sky...
Published 07/12/11