According to Alphonse Sterling, astrophysicist from NASA’s Marshall Space Flight Center in Huntsville, Alabama, total lunar eclipses occur approximately once every 1.5 years on average. While the Moon has been providing generous eclipse viewing opportunities this year, viewers should take advantage of November’s eclipse because the next total lunar eclipse will not occur until 2025.
The Flower
Moon lunar eclipse over NASA’s Michoud Assembly Facility in New Orleans is
shown from the initial partial eclipse to totality in a composite of seven
images shot on Sunday, May 15, 2022. Image credit: NASA/Michael DeMocker
A total lunar eclipse occurs when Earth
casts a complete shadow – called an umbra – over the Moon. Earth’s shadow is
categorized into two parts: the umbra, the innermost part of the shadow where
direct light from the Sun is completely blocked, and the penumbra, the
outermost part of the shadow where the light is partially blocked.
During a total lunar eclipse, the Moon
and the Sun are on opposite sides of Earth. Many people wonder why lunar
eclipses don’t happen every month given the Moon completes an orbit around
Earth every 27 days. The reason is because the Moon’s orbit around Earth is
tilted relative to Earth’s orbit around the Sun, so the Moon often passes above
or below Earth’s shadow. Lunar eclipses are only possible when the orbits align
so that the Moon is directly behind Earth relative to the Sun.
For North America the action will start
in the early hours of the morning on Nov. 8. The partial eclipse will begin at
3:09 a.m. CST, with totality beginning at 4:16 a.m. and ending at 5:42 a.m.
Then, the partial phase will resume, lasting until 6:49 a.m. Those in the
eastern part of the United States will miss most or all of the last partial
phase because the Moon will set during totality or shortly after totality ends.
Another feature of a total lunar eclipse
is the Moon’s red hue during totality. The red color occurs because of the
refraction, filtering, and scattering of light by Earth’s atmosphere. The
scattering is a phenomenon called Rayleigh scattering – named after the
19th-century British Physicist Lord Rayleigh.
Rayleigh scattering is also the reason
for red sunrises and sunsets. Light from the Sun collides into the gases of
Earth’s atmosphere and because of its shorter wavelength, blue light is
filtered out, but red light is not easily scattered because of its longer
wavelength. Some of that red light is refracted, or bent, as it passes through
Earth’s atmosphere and ends up shining on the Moon with a ghostly red light.
The degree of redness of a fully eclipsed Moon can be influenced by atmospheric
conditions resulting from volcanic eruptions, fires, and dust storms.
A nearly
total eclipse of November’s full “Beaver Moon” captured over the city of New
Orleans before dawn on Nov. 19, 2021. The 97% eclipse clocked in at 3 hours, 28
minutes, and 24 seconds, making it the longest partial lunar eclipse in 580
years. Credits: NASA/Michoud Assembly Facility
But what does Earth look like from the
Moon’s perspective during a lunar eclipse? According to Mitzi Adams,
astrophysicist at Marshall, astronauts on the Moon during a total lunar eclipse
would see a red ring around a silhouetted Earth. As NASA works to establish a
permanent human presence on the Moon through the Artemis program, it’s fascinating to consider how Earthlings will
experience astronomical events away from their home planet.
No special eye protection is needed for
viewing a lunar eclipse, unlike solar eclipses (which occur during the
daytime). While the lunar eclipse can be observed with the unaided eye, a pair
of binoculars or a telescope can enhance the view.
Sterling says a fun activity for those who stargaze with family or friends is to discuss who notices the reddish hue of totality first and how it progresses throughout the eclipse.
Gain more understanding of lunar eclipses, learn about NASA’s observations of eclipses, and inspire young stargazers with activities and information.
Source: Last Chance to See Total Lunar Eclipse Until 2025! – Watch the Skies (nasa.gov)
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