Astronomers around the world will have the opportunity to see a blood moon over the weekend as a lunar eclipse moves through Earth’s orbit.
The penumbral eclipse, when the moon is fully immersed in Earth’s penumbral cone without touching the umbra, the inner part of Earth’s shadow, is expected to begin just after 9:30 p.m. ET on Sunday, according to NASA. The penumbral eclipse darkens only part of the moon.
The partial eclipse, when the moon appears to be moving into shadow and part of the moon inside the shadow will appear very dark, will occur just before 10:30 p.m. ET.
Totality will begin just before 11:30 p.m. ET, when the entire moon is inside Earth’s shadow and turns a copper-red hue. Totality will end before 1 a.m. Monday, and the penumbral eclipse will end at 2:50 a.m.
Residents of the eastern half of the United States and all of South America will be able to observe every stage of the lunar eclipse, and totality will be visible over much of Africa, Western Europe, South America. Central and South America and most of North America, according to NASA.
A dark environment away from bright lights will provide the best viewing conditions.
A lunar eclipse occurs when the sun, Earth, and moon align and the moon passes into Earth’s shadow, according to NASA. “Blood Moon” is the term to describe the part of the total lunar eclipse in which all of Earth’s sunrises and sunsets are projected onto the moon’s surface as it passes through the Earth’s shadow, l darkening and giving it its crimson color.
Rayleigh scattering, the same phenomenon that gives the sky its blue color and makes sunsets red, is what causes the moon to turn red during the eclipse. Red light, which has longer wavelengths than blue light, is seen during a lunar eclipse because the only sunlight reaching the moon passes through Earth’s atmosphere, according to NASA.
“It’s as if all the sunrises and sunsets in the world are projected onto the Moon,” according to the administration.
The more dust or clouds in Earth’s atmosphere at the time of the eclipse, the redder the moon will appear.
During the eclipse, cloud cover is expected from Dallas to Chicago, while scattered clouds will extend from Atlanta to New York. NASA will broadcast a live feed of the total lunar eclipse.
The next total lunar eclipse will be on November 8. After that, another total lunar eclipse will not occur until March 13, 2025.