1 00:00:00,180 --> 00:00:03,700 When the new moon passes exactly in front of the sun, 2 00:00:03,700 --> 00:00:05,700 its shadow crosses the Earth. 3 00:00:06,580 --> 00:00:09,740 The deepest part of the shadow is called the umbra. 4 00:00:10,140 --> 00:00:13,780 People in the umbra see a total solar eclipse. 5 00:00:14,020 --> 00:00:17,300 It takes about an hour for the shadow to cross the earth. 6 00:00:18,840 --> 00:00:23,280 Two weeks later, the full moon can cross into Earth’s umbra. 7 00:00:23,780 --> 00:00:27,460 Since the Earth is four times the diameter of the Moon, 8 00:00:27,460 --> 00:00:32,540 the umbra is also four times larger or 16 times the area. 9 00:00:33,220 --> 00:00:37,680 So lunar eclipses are more common than solar eclipses. 10 00:00:38,320 --> 00:00:42,780 Everyone on the nightside of Earth can see a total lunar eclipse. 11 00:00:43,200 --> 00:00:46,360 But only people in the narrow strip of totality 12 00:00:46,360 --> 00:00:49,040 can see a total solar eclipse. 13 00:00:49,360 --> 00:00:53,060 So, not only are lunar eclipses more common, 14 00:00:53,060 --> 00:00:56,200 more people can observe each one.