Hobbies And Interests
Moon
The moon is Earth's only natural satellite and orbits us completely every 29.5 days. The moon goes through a series of phases during this period. During a new moon, all of the moon is obscured by darkness. A crescent moon has most of its face obscured, apart from an illuminated crescent. A gibbous moon has most of its face illuminated, apart from a crescent that is in darkness. A full moon is completely illuminated.
Lunar Eclipse
A lunar eclipse occurs when the sun, Earth and moon line up, in that order. When the moon passes through the Earth's shadow, it is known as a lunar eclipse. There are two parts to the shadow: the penumbra and the umbra. The penumbra is a partial shadow that only slightly reduces the moon's brightness. In the umbra, all direct light from the sun is blocked and the moon appears to dim considerably more.
Red Moon
When the moon passes through the umbra, it is still visible, but looks red instead of its usual white color. This is because the light from the sun passes through Earth's atmosphere and is scattered by it. The extent of the scattering depends on the wavelength of the light, with shorter wavelengths scattering more. Blue light has the shortest wavelength, so it is scattered the most. Light that reaches the moon during an eclipse has had to pass through more atmosphere than usual. As the blue light scatters, red light, which has a longer wavelength, remains. It is therefore mostly red light that illuminates the moon during a lunar eclipse, giving it a red appearance.
Light Scattering
At sunset, the sky often appears pink or red for the same reason the moon does during a lunar eclipse. During the day, however, the sky appears blue. In the daylight, light has less atmosphere to pass through, so the light is scattered less. We see all colors of light from the sun because it is directly overhead, and the sky appears blue from the scattered blue light.