In the wee hours of Tuesday, residents in the Bay Area will be able to witness a spectacular total lunar eclipse — often called a “blood moon,” due to its deep red hue.
This celestial event happens when the Earth moves directly between the sun and the moon, casting a shadow that darkens the moon and turns it a striking shade of red during totality.
And unlike solar eclipses, you can enjoy the lunar eclipse with the naked eye: no protective viewing glasses required.
“Total eclipses of the moon are very democratic,” Andrew Fraknoi, astronomer and professor at the University of San Francisco’s Fromm Institute, told KQED by email — calling them “easy to spot, perfectly safe to look at, and not requiring any special equipment to see.”
A lunar eclipse is visible to anyone on the night side of Earth. In contrast, total solar eclipses are only visible along a narrow path of totality — sometimes just a few hundred miles wide.
As long as you’re somewhere where you have a clear view of the moon, the upcoming total lunar eclipse will be fully visible across the Bay Area.
It will begin at around 1:50 a.m. PST on March 3, and totality will occur at 3:04 a.m. The maximum eclipse — when the moon will be its reddest — will occur at 3:33 a.m. and last for about 30 minutes into the early hours.
“As the moon moves slowly through the Earth’s shadow, we first see only part of the moon darkening,” Fraknoi said of the partial eclipse. “But then, as the moon moves fully into the Earth’s shadow, we see its entire disk of the moon become dark and reddish.”
This means that the best blood moon views occur between 3:04 a.m. and 4 a.m. After that, the moon will wrap up shortly before 5 a.m., when it exits Earth’s shadow.
“The unfortunate thing is that all the time zones will see the eclipse in the ‘middle of the night,’ which might lead to some very tired coworkers or students coming in the next morning,” Fraknoi said.
During totality, the moon glows red because of Rayleigh scattering: the same phenomenon that makes sunsets appear orange and red.
As sunlight passes through Earth’s atmosphere, it filters out blue light and bends red light toward the moon, giving it that signature “blood” color.
The exact shade of red depends on atmospheric conditions like dust, pollution and volcanic activity elsewhere, which can intensify the red hue, Fraknoi said.
Astronomers have been able to predict lunar eclipses centuries — even millennia — in advance using precise models of the Earth-moon system. Ancient skywatchers tracked repeating eclipse patterns known as the Saros cycle, which recurs roughly every 18 years.
Today, space agencies use detailed orbital calculations to forecast eclipses down to the minute.
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