"Blood moon" (Image 4)
A luner eclipse that took place April 15, 2014, as photographed in Tucson, Ariz.
A lunar eclipse occurs when the moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth and moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. Unlike a solar eclipse, which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth.
Nicknamed a "blood moon," this lunar eclipse's color was similar to the majority of lunar eclipses. This has to do with the Earth's atmosphere's propensity for longer-wavelength light (e.g., the reds, oranges and yellows seen in sunrises and sunsets).
"The study of the color of lunar eclipses can be used to understand dust in the stratosphere including the amount and particle size of dust injected by volcanic eruptions," says Stephen Pompea, an astronomer at the National Optical Astronomer Observatory. "Understanding the amount of dust can help scientists create better models of climate change." (Date image taken: April 15, 2014; date originally posted to NSF Multimedia Gallery: Nov. 12, 2015) [Image 4 of 4 related images. Back to Image 1.]
Credit: Stephen Pompea, NOAO
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