Archaeoastronomy: The study of the knowledge, interpretations, and practices of ancient cultures regarding celestial objects or phenomena.
Ancient ObservatoriesLast Updated on 2008-06-11 00:00:00
There is an astronomical context for understanding mysterious structures like Stonehenge. Keeping a calendar was a vital job for any ancient culture. We can imagine that an enormous effort would be put into measuring and marking the changing seasons. In the absence of true understanding, we can also imagine that these structures would have a ceremonial purpose. Today, most astronomers and archaeologists agree that Stonehenge was built as a marker or ceremonial site, dedicated to observing the date of summer solstice. The avenue points from the center of Stonehenge to the position of sunrise on June 21st. Someone standing in the center of Stonehenge could see the Sun rise over a big stone, called the heel stone, on the day of solstice. (The mysterious name, "heel stone," may have come in ancient times from the Greek root, helios, for Sun.) Still more astronomical purposes have been... More »
Lunar Eclipse - February 20, 2008Last Updated on 2008-02-28 00:00:00During the evening of February 20th, a total lunar eclipse will begin at 5:45 p.m. PST / 8:45 p.m. EST. The next total lunar eclipse won't be until 2010.
"A lunar eclipse occurs when the Earth lines up directly between the sun and the moon, casting a shadow over the moon's surface. The February 20, 2008 eclipse will last for nearly 3 and a half hours. For a full 50 minutes of that time the moon will be in totality - the period when the lunar surface is completely covered by the Earth's shadow."
"During an eclipse the moon changes color, going from a light gray color to an orange or deep red shade. This is totality. The moon takes on this new color because indirect sunlight is still able to pass through the Earth's atmosphere and cast a glow on the moon."
Figure 1. This map shows when the eclipse will be visible across the United States. Image credit: NASA.
"The exact color that... More »
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