|
Total Lunar Eclipse: A total lunar eclipse occurs when the Moon passes through the Earth's umbral shadow. Because the Earth's diameter is about four times as large as the Moon's, during a total lunar eclipse the Earth's umbra is large enough to completely cover the Moon's disk for up to an hour or more. At totality, no part of the Moon's surface is in the Sun's light. Yet the Moon does not simply become dark. Instead, it may turn a coppery red color. The Earth's atmosphere plays a role in bending some of the Sun's red light into Earth's umbra, much as light is bent by a prism. As the Sun's light passes through the Earth's atmosphere, much of the blue light contained in the sunlight is "scattered" in the atmosphere. Robbed of a significant portion of its blue light, the sunlight that passes through the Earth's atmosphere is mostly the remaining colors of yellow, orange, and red. So the light that has been bent and reddened by the Earth's atmosphere arrives at the Moon to bathe its surface in an orange-red glow.
 Partial Lunar Eclipse: Not all lunar eclipses are total eclipses. Depending on the positions of the Sun, Earth, and Moon as the Moon orbits the Earth and the Earth orbits the Sun, the Moon may pass through the Earth's umbra only partially, or through the penumbra only. Though not as spectacular as total eclipses, partial lunar eclipses are nevertheless notable lunar events.
|
