Astronomy September 9, 2008 Lecture 5 • The atmosphere around the earth bends sunlight, and so sunlight passing through the atmosphere on the edge of the earth gets bent into what would otherwise be the completely dark umbra. This light falls on the moon, and this light is what allows you to see the moon during a lunar eclipse. The blue light is removed in the atmosphere (the atmosphere scatters it), leaving only the red light, thus making a lunar eclipse red. • New, waning crescent, last quarter, waning gibbous, full, waxing gibbous, 1 st quarter, waxing crescent, new. • Moon has two periods- rotation period, and its phase period. o The 360 degree period is called the sidereal period. This is 27.3 days. o The synodic period is the period of phases. Based of position of object in question, and position of sun. This is 29.5 days. • Eclipse seasons- periods of the year when you can have eclipses, and periods when you cannot have eclipses. Periods where you CAN have them are called
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Eclipse seasons- periods, completely dark umbra, periods- rotation period