A lunar eclipse occurs when the Earth passes directly between the Sun and the Moon, causing the Earth’s shadow to be cast on the surface of the Moon. This phenomenon can only happen during a full moon, when the Sun, Earth, and Moon are aligned in a straight line, with the Earth in the middle.
There are two main parts to Earth’s shadow that contribute to a lunar eclipse:
- Penumbra: The outer part of the shadow, known as the penumbra, is a lighter, partial shadow. When the Moon passes through the penumbra, it may darken slightly, but this is usually not very noticeable, and it is called a penumbral eclipse.
- Umbra: The inner part of the shadow, called the umbra, is a much darker, total shadow. When the Moon moves into the umbra, it is completely hidden from direct sunlight, causing a total lunar eclipse. The Moon can appear to change color during a total lunar eclipse, often taking on a reddish or copper hue, which is commonly referred to as a “blood moon.” This effect is due to the Earth’s atmosphere scattering and refracting sunlight, allowing longer-wavelength red and orange light to reach the Moon while shorter wavelengths are scattered.
The occurrence of lunar eclipses is a result of the relative positions and movements of the Earth, Moon, and Sun in their orbits. Lunar eclipses are a fascinating celestial event and are safe to observe with the naked eye, making them accessible for stargazers and skywatchers.