How to see the blood moon total lunar eclipse in the Bay Area

Sunset in the Bay Area this Sunday will come with a rare treat: a blood moon, during a total lunar eclipse.

What’s more, since the moon will be near its perigee, or closest point to Earth, it will also be considered a “supermoon.”

And in May, the full moon is referred to as the “flower moon” by the Old Farmer’s Almanac, citing Native American, Colonial American and other traditional North American sources for the term acknowledging the abundance of spring blooms.

That all adds up to a “super flower blood moon.” So, there’s a lot going on here – but any way you look at it, the event promises to be spectacular in the Bay Area.

The moon will already be in a partial eclipse when it rises on the West Coast at 8:06 pm, just four minutes before sunset. The total eclipse starts at 8:30 pm and lasts until 9:54 pm, and the ensuing partial eclipse ends around 10:50 pm, said Andrew Fraknoi, the emeritus chair of the astronomy department at Foothill College.

So although it won’t be completely dark when the moon first rises, it’ll be one of the rare times an entire total eclipse is visible from the West Coast.

“We’ll miss some of the early parts of the eclipse where the shadow is slowly moving over the face of the full moon, but kids will be able to see it (because it’s early in the night),” Fraknoi said. “There’s some price to pay but a very nice reward.”

Seeing the eclipse doesn’t require special equipment, but if you want the clearest view in the Bay Area, consider heading to a higher elevation point such as Twin Peaks.

“It’s very democratic – you don’t need special equipment or expensive telescopes. All you need is your eyes,” Fraknoi said.

A lunar eclipse occurs when the Earth is between the sun and the moon, and the moon moves through the Earth’s shadow. The total eclipse occurs when the entire moon falls into the Earth’s umbra, the darkest part of its shadow, according to NASA.

However, the moon isn’t totally blacked out. Some light from the sun reaches the moon after passing through the Earth’s atmosphere, where air pollution acts like a prism, causing the moon to appear red – hence the “blood moon” nickname.

On Sunday, the moon will rise from the southeastern horizon and become darker and redder as it climbs into the sky.

“The Earth’s shadow is not completely dark because the refracted red light coming through the atmosphere goes into the darkest part of the Earth’s shadow and produces that red color,” said Gerald McKeegan, an adjunct astronomer with the Chabot Space and Science Center in Oakland.

Observing a total lunar eclipse in the early night in the Bay Area is uncommon – the next one occurs in early November, but will be visible on the West Coast only between 1 and 6 am

There’s another bonus for sky watchers: The darkened moon may make it easier to spot stars and bright planets in the sky, such as Mars, Venus and Jupiter. The moon will be in the constellation Libra when the eclipse occurs.

However, keep in mind that although it’s a “supermoon,” it won’t appear visibly larger to the naked eye, Fraknoi said. Though the supermoon is closer to Earth than a normal full moon and technically appears about 7% larger, even if you could see it side by side with a normal moon there would be little if any difference, he said.

May has been a busy month in the night sky, starting with the Eta Aquarids meteor shower. A never-before-seen meteor shower called the Tau Herculids might be visible at the end of the month.

Gwendolyn Wu (she/her) is a San Francisco Chronicle staff writer. Email: gwendolyn.wu@sfchronicle.com

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