The moon will turn red during the total lunar eclipse this Sunday evening
In two years, a full solar eclipse will travel from Texas to Maine
This is the first of two total lunar eclipses visible from the United States this year. The next one is scheduled for the night of Nov. 7 and will favor parts of northwestern North America that will miss the Sunday night show.
What is a total lunar eclipse?
Eclipses of all shapes occur when one object blocks another. In the case of a total lunar eclipse, the Earth comes between the sun and the moon. You might expect this to block sunlight from reaching the moon, causing it to disappear, but it doesn’t. Instead, some of the sunlight brushes Earth’s periphery through our atmosphere and is scattered toward the moon.
For this to happen, the sun, earth, and moon must all be aligned. This only happens during the full moon.
Total solar eclipses, on the other hand, occur during new moons, when the moon slips between Earth and the sun. This prevents sunlight from reaching a narrow corridor of the Earth, turning day into night. Solar eclipses also allow the emergence of the sun’s milky white corona, or atmosphere, usually eclipsed by blazing sunlight.
Solar and lunar eclipses occur 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 mundane “penumbral” lunar eclipse – a subtle darkening barely noticeable to the untrained observer. This is when the broadest and most diffuse part of the Earth’s shadows begins to sweep across the lunar surface from bottom left to top right.
The partial phase of the eclipse will ensue, when the edge of the shadow, or the darkest part of the Earth’s shadow, first makes contact with the moon. You will see a veil of darkness cross the moon, its edge a gentle curve representing 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 completely, the moon will turn red. This is because the only light reaching the moon is that which passes through the earth’s atmosphere. The shorter wavelengths/higher frequencies of light are scattered, leaving only the longer, red-colored wavelengths able to penetrate through the length of the atmosphere at a low angle of incidence . It’s the same premise that makes sunrises and sunsets red. Therefore, you see the light of the always simultaneous sunrise and sunset projected onto the moon.
The maximum eclipse occurs when the moon is most firmly buried in Earth’s shadow, immersed in nothing but a strange red light. The color of a lunar eclipse actually varies depending on the pollution of the atmosphere; astronomers assess tonal hues on the Danjon scale, where a zero corresponds to a barely visible eclipse and a four to a copper-rust. Volcanic eruptions and the presence of aerosols are known to reduce the vibration of lunar eclipses.
All times provided are in Eastern Time:
Begin penumbral eclipse: 9:32:05 p.m. Eastern Time
Start partial eclipse: 10:27:52 p.m. Eastern Time
Start the whole: 11:29:03 p.m. Eastern Time
Maximum eclipse: 12:11:28 a.m. Eastern Time
End of totality: 12:53:55 a.m. Eastern Time
End of the partial eclipse: 1:55:07 a.m. Eastern Time
End of the penumbral eclipse: 2:50:49 EST
To note: For some on the west coast, the moon will not rise until totality is already underway. Moonrise in San Francisco, for example, is scheduled for 8:06 p.m. PT, just 23 minutes before totality begins.
What is special about 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 receive one or two total lunar eclipses per year.
Total solar eclipses, on the other hand, are only visible from a given location once every 375 years on average. The path to totality can be a ribbon 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.
Patches of cloud will be scattered intermittently over the East Coast, Intermountain West, Sierra Nevada and Pacific Northwest. The center of the country will see large expanses of clear skies suitable for viewing.
A more refined prediction will be made in the coming days.