First segment of NASA Connect Ancient Observatories explaining the foundations of astronomy and the how the Earth moves relative to the sun. This segment explains how the Earth's tilt creates the 4 seasons.
Second segment of NASA Connect Ancient Observatories explaining how the height of the sun relates to the growing seasons and the length of daylight. This segment describes how Ancient Egyptian and Greek cultures used astronomy in their lives. The segment also contains an activity for exploring how a gnomon works. In the activity students must track the shadows made by a gnomon in 30 minute intervals. The activity will teach students how the length of the shadows and the angles created by the gnomon are related to the position of the sun.
Third segment of NASA Connect Ancient Observatories that shows two examples of how the Navajo used used structures to track progress of the sun in the sky.
Fourth segment of NASA Connect Ancient Observatories describing the Ancient Mayan civilization and their accomplishments. This segment compares the Mayan counting system to the Roman counting system and has a brief exercise for students to add the numbers 21 and 33 using both systems.
The strongest magnetic field in nature is from the magnetar star SGR 1806-20, which has been estimated as 800 trillion Gauss.