Lunar eclipses
A lunar eclipse is an astronomical event that occurs when the Moon orbits through Earth's shadow. Unlike solar eclipses, which are brief and visible only from specific locations, lunar eclipses can be observed from anywhere on the night side of Earth and often last for an hour or longer. They are also safe to observe without eye protection. During a total lunar eclipse, the Moon often appears orange or red due to a process called Rayleigh scattering, where sunlight passes through Earth's atmosphere before reaching the Moon, removing shorter wavelengths and leaving longer red wavelengths. This phenomenon matters because it demonstrates Earth's position relative to the Sun and Moon, has been used historically to prove Earth's round shape, and provides spectacular celestial viewing opportunities for skywatchers worldwide.
Sources
- en.wikipedia.org: “A lunar eclipse, also called a blood moon, is an astronomical event that occurs when the Moon orbits through Earth's shadow.”
- en.wikipedia.org: “In contrast with elusive and short-lasting solar eclipses, lunar eclipses can be observed from anywhere on the night side of Earth and often last for an hour or longer.”
- en.wikipedia.org: “Lunar eclipses are safe to observe without eye protection.”
- en.wikipedia.org: “Lunar eclipses cause the Moon to appear orange or red. This occurs because when the Moon passes through the Earth's umbra, any sunlight that reaches the Moon must first pass through the Earth's atmosphere. The resulting Rayleigh scattering removes short-wavelength colors such as violet and blue from the light before it reflects back off the lunar surface and is observed on Earth.”
- en.wikipedia.org: “Ancient Greeks understood the Earth was round, citing the Earth's shadow observed during a lunar eclipse as evidence.”