A lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon. There are three main phases of a lunar eclipse:
1. Penumbral Phase: This is the initial phase of the lunar eclipse. During this phase, the Moon enters the Earth's penumbra, which is the outer part of the shadow. The penumbra is not as dark as the inner shadow, so the changes in the Moon's appearance are subtle.
2. Partial Phase: In this phase, the Moon moves deeper into the Earth's shadow, known as the umbra. The umbra is the darker, inner part of the shadow. As the Moon passes through the umbra, a portion of it becomes obscured, resulting in a partial eclipse. The exact amount of the Moon's surface covered by the shadow varies during a partial eclipse.
3. Total Phase: This is the most visually striking phase of a lunar eclipse. When the Moon is fully within the Earth's umbra, it is entirely in shadow, resulting in a total lunar eclipse. During this phase, the Moon often takes on a reddish or coppery hue, earning it the nickname "blood moon." This reddish color is caused by the Earth's atmosphere bending sunlight and scattering shorter blue wavelengths while allowing longer red wavelengths to reach the Moon.
After the total phase, the Moon gradually moves out of the Earth's shadow, reversing the sequence of phases until the lunar eclipse concludes.
It's important to note that a lunar eclipse can be observed from anywhere on Earth where the Moon is visible during the event, unlike a solar eclipse, which is visible only from specific regions where the Moon's shadow falls on the Earth's surface.