How to watch Thursday’s unusual lunar eclipse in California skies

The vast majority of the moon will dip into Earth’s coppery red shadow on Thursday evening, forming a deep partial lunar eclipse.

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Anyone in California with a view of the moon and clear skies can see this phenomenon with the naked eye, though binoculars will add color and detail.

The heart of the eclipse will start at 7:34 p.m., minutes before the moon rises in the Bay Area. About 96% of the moon will turn rusty as the event culminates at 9:13 p.m.

“This eclipse just misses totality, and that is its charm,” E.C. Krupp, the director of Griffith Observatory in Los Angeles, wrote to SFGATE. “… It should look a lot like a total lunar eclipse, coppery red with a pearly highlight on top.”

During a lunar eclipse, the moon is full. When Earth is directly between that full moon and the sun, its shadow dims the moon. The Earth’s shadow has two elements, an outer faint one — the “penumbra” — and an inner, darker “umbra.” On Thursday, the moon will pass through the umbra — which turns the surface a shade of red, thanks to the refraction of sunlight through Earth’s atmosphere — between 7:34 p.m. and 10:52 p.m.

The same phenomenon that colors the moon reddish-orange during a lunar eclipse fuels sunsets and sunrises. “The red is the light of all of the world’s sunrises and sunsets bent by the earth’s atmosphere onto the face of the shadow-darkened moon,” Krupp explained.

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However, the classic August weather in San Francisco might make viewing these colors difficult. When asked about the chance of clear skies in the San Francisco Bay Area on Thursday evening, National Weather Service meteorologist Rachel Kennedy replied: “You probably will not be happy with the answer.” As of Tuesday afternoon, the forecast showed a good chance of fog and high clouds rolling into the Bay Area on Thursday evening.

Southern California residents might have a slightly better chance of clear skies, according to Mike Wofford, a weather service meteorologist in Los Angeles.

If clouds hang over your backyard in the Bay Area, you can instead try tuning in to the Griffith Observatory’s livestream from 7:25 p.m. to the lunar event’s official end by 12:05 a.m.

The next total lunar eclipse visible from California won’t happen until June 2029, according to Gerald McKeegan, an adjunct astronomer for Chabot Space & Science Center.