2. Ancient Astronomy and Celestial Phenomena

Transcript: What would you observe if you looked at the sky for a year from somewhere in the Northern hemisphere?  You'd... Read more

Transcript: The apparent position of the Sun in the sky depends on your position on the Earth's surface.  The regions be... Read more

Transcript: Eclipses occur due to the coincidence that the sun and the moon have the same apparent angular size in the s... Read more

Transcript: Socrates was an enormously influential Greek philosopher even though he wrote nothing down. Socrates was no... Read more

Transcript: Plato was a disciple of Socrates. He founded the world’s first university in an olive grove outside Athens i... Read more

Transcript: The seasons are caused by the tilt of the Earth’s spin axis as it orbits the Sun. If there were no tilt of ... Read more

Transcript: It is fundamental to how science works, and to our understanding of the everyday world, that events have cau... Read more

Transcript: Pythagoras was one of the most influential thinkers in history. This Greek philosopher and mathematician ca... Read more

Transcript: A sidereal day is a period of the Earth’s rotation with respect to the celestial sphere, the time it takes f... Read more

Transcript: Major calendar reform occurred around the time of Julius Caesar in 44 BC.  The early Roman calendar was very... Read more

Transcript: By the late 16th Century, the Julian calendar was out of sync with the seasons. With an average length of 3... Read more

Transcript: The fundamental issue of calendars comes down to two astronomical numbers. One is the solar year, the time ... Read more

Transcript: When you think of the calendar that we use every day some questions arise.  Why do you have to count on your... Read more

Transcript: Empedocles supposed that all material was composed of four fundamental substances, earth, air, fire and wate... Read more

Transcript: We always see the same features on the surface of the Moon.  This means that the Moon's rotational period eq... Read more

Transcript: The patterns and motions of the stars in the night sky can be used for navigation. In the Northern Hemisphe... Read more

Transcript: The moon does not emit its own light. All the light we see from the moon is reflected sunlight. The phases... Read more

Transcript: Many cultures have used a solar calendar, and, in fact, Sun worship was a basic part of ancient civilization... Read more

Transcript: Every human culture has felt the need to subdivide time. In addition to the seasons, which follow from the E... Read more

Transcript: The constellations of the night sky are among the oldest human artifacts.  For thousands of years humans hav... Read more