It is the first of two total lunar eclipses visible from the United States this year. The next one is scheduled for the evening of November 7 and will favor parts of northwestern North America that will miss out on the Sunday night show.
What is a total lunar eclipse?
Eclipses of all forms occur when one object blocks another. In the case of a total lunar eclipse, the Earth intercedes between the sun and the moon. You might expect that to block sunlight from reaching the moon, making it disappear, but that doesn’t happen. Instead, some sunlight slips past Earth’s periphery through our atmosphere and scatters toward the moon.
For this to happen, the sun, earth, and moon must be aligned. That only happens during a full moon.
total solar eclipses, on the other hand, take place during new moons, when the moon slips between the Earth and the sun. That blocks sunlight from reaching a narrow corridor on Earth, turning day into night. Solar eclipses also allow the appearance of the sun’s milky-white corona or atmosphere, normally eclipsed by sunlight.
Solar and lunar eclipses come in pairs about two weeks apart; the most recent partial solar eclipse, on April 30, was visible from South America.
The total lunar eclipse will begin as a nondescript “penumbral” lunar eclipse, a subtle dimming barely noticeable to the inexperienced observer. That’s when the widest, most diffuse part of Earth’s shadows begin to sweep across the lunar surface from lower left to upper right.
The partial phase of the eclipse will occur, when the edge of the umbra, or the darkest part of the Earth’s shadow, first makes contact with the moon. You will see a veil of darkness across the moon, its edge a smooth curve that represents the shape of the Earth. The curve of the shadow will be smoother than that of the moon, since the Earth is larger.
Once the shadow swallows it whole, the moon will turn red. That’s because the only light that reaches the moon is that which passes through Earth’s atmosphere. The shorter wavelengths and higher frequencies of light are scattered, leaving only the longer, red-colored wavelengths capable of penetrating through the atmosphere at a low angle of incidence. It is the same premise that makes sunrises and sunsets red. Therefore, you are seeing the light of the ever-simultaneous sunrise and sunset projected onto the moon.
The maximum eclipse occurs when the moon is buried more firmly within Earth’s shadow, immersed in nothing but eerie red light. The color of a lunar eclipse actually varies depending on how polluted the atmosphere is; astronomers qualify the tonal hues in the danjon scale, for which a zero corresponds to a barely visible eclipse and a four represents a coppery oxide one. Volcanic eruptions and the presence of aerosols are known to reduce the vitality of lunar eclipses.
All times provided are in Eastern Time:
The penumbral eclipse begins: 21:32:05 Eastern Time
Partial eclipse begins: 22:27:52 Eastern Time
Start totality: 23:29:03 Eastern Time
Maximum eclipse: 12:11:28 Eastern Time
Final totality: 12:53:55 a.m. Eastern Time
Final partial eclipse: 1:55:07 a.m. Eastern Time
Final penumbral eclipse: 2:50:49 a.m. Eastern Time
Note: For some on the west coast, the moon won’t rise until totality is already underway. Moonrise in San Francisco, for example, is scheduled for 8:06 p.m. Pacific Time, just 23 minutes before totality begins.
How special are total lunar eclipses?
Lunar eclipses are not as special as total solar eclipses. Lunar eclipses can be seen from all over the night side of the Earth, since the moon is visible from anywhere. Most places have one or two total lunar eclipses per year.
Total solar eclipses, on the other hand, are visible from a given location only once every 375 years on average. The path of totality can be a strip of barely a mile wide, and the experience is surreal. The next one to be seen in the United States will be on Monday, April 8, 2024.
Cloud patches will intermittently scatter along the East Coast, Intermountain West, Sierra Nevada, and Pacific Northwest. The center of the country will see large stretches of clear skies favorable for observation.
A more refined prediction will be made in the coming days.