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Bay Area residents to experience partial eclipse Thursday

 

On Thursday afternoon, Bay Area residents and visitors will be able to view a partial eclipse of the sun in the southwestern sky, but experts warn that looking at the sun for more than a glance without proper protection or a filter can damage eyes.

Many observatories, science centers and colleges in the Bay Area are holding viewing parties where people can view the eclipse using a filter or other protective equipment.

"It's really a fun event," said Foothill College astronomer Andrew Fraknoi.

He said the eclipse will look "like a giant black bite being taken out of the sun."

The best time to view the eclipse locally is between 3 p.m. and 3:30 p.m. At 3:15 p.m., about 40 percent of the sun will be covered, the maximum amount that will be covered in this event.

The eclipse will begin in the Bay Area at 1:52 p.m. and end at 4:32 p.m., according to astronomers.

An eclipse of the sun happens when the moon gets between the sun and Earth and covers up some or all of the sun.

"They don't happen every day," said Ben Burress, staff astronomer at the Chabot Space & Science Center in Oakland. Burress added that most eclipses are partial eclipses and Bay Area residents and visitors may see the earth's sunlight dim Thursday.

Other eclipses go without notice among a majority of the population, Burress said.

The Foothill College Observatory in Los Altos Hills will open at 2 p.m. for an eclipse party and safe viewing. The Chabot Space & Science Center will be open to viewers at 1:45 p.m.

On their own, viewers can use special glasses or create a way to project the sun to view the eclipse.

The best way, Fraknoi says, is to make a pinhole projector by taking two pieces of thick paper or cardboard and making a clean pinhole in one. Facing away from the sun, people can hold the cardboard or paper with the hole in it and allow the sun to project an image through the pinhole onto the other paper.

To get a sharper image, people can cut a square in one of the pieces of paper or cardboard, tape a sheet of aluminum foil over the square hole and poke a pinhole in the foil. Allow the sun to pass through the hole in the foil.

Nowhere on earth will the eclipse be total, Fraknoi said.

Comments

Like this comment
Posted by Question
a resident of Another Palo Alto neighborhood
on Oct 22, 2014 at 10:59 am

We have special eclipse glasses for eyes and camera - they say they are safe, and we used them comfortably with the last eclipse, are there any issues with those? Any issues since they are a few years old?


Like this comment
Posted by Resident
a resident of Another Palo Alto neighborhood
on Oct 22, 2014 at 11:27 am

Hold a colander, or anything with a circular hole, to form a shadow on the ground. Choose a place that is smooth like concrete. Look at the shape of the "circular" hole in the shadow. It should be crescent shaped during the partial eclipse.

Other shadows like through a net curtain or a leafy bush, will be strange too.


1 person likes this
Posted by musical
a resident of Palo Verde
on Oct 22, 2014 at 3:39 pm

The sun's image can be disappointingly small and dim and fuzzy with the pinhole technique. Although it will show the basic eclipse progress, five feet behind a pinhole the sun's disk is still smaller than a dime.

Projecting through half a pair of binoculars gives a comparably spectacular image, but is best left to someone with experience in keeping bystanders from attempting to look directly through the eyepiece with catastrophic results.
Plenty of instructions are available on-line, e.g. Web Link

A surprise is in store for people seeing a good image -- there is a large sunspot group that should be centered just south of the solar equator. More awesome to me than the rings of Saturn. See Web Link for a preview. Side note: many of the scientific instruments monitoring the sun are built right here in Palo Alto.


1 person likes this
Posted by don't look at the sun
a resident of Midtown
on Oct 22, 2014 at 3:48 pm

Apart from damage to your eyes, looking directly at the sun is pretty boring anyway. Much more fun is to hold various objects (even tree branches) up in front of the sun, then look at the distorted shadows you get on the ground because of the eclipse.


Like this comment
Posted by Question
a resident of Another Palo Alto neighborhood
on Oct 22, 2014 at 8:36 pm

The last eclipse -- those eclipse glasses were actually pretty cool, and I took some neat photos with the camera version. The biggest concern is to be sure to have something to shade your face otherwise, it turns out the sun is still pretty hot.

We seem not to have suffered any ill effects of the "eclipse glasses" -- can anyone please comment if there are any concerns?

Too late to get these online, but this is them:
Web Link


Like this comment
Posted by Mike Alexander
a resident of St. Claire Gardens
on Oct 22, 2014 at 9:03 pm

#14 welder's glass is safe. Madco in Mtn View usually stocks up for eclipses. To be safe, a filter has to block nearly all visible AND infrared light. Thorough technical discussion at Web Link


Like this comment
Posted by Mike Alexander
a resident of St. Claire Gardens
on Oct 22, 2014 at 9:08 pm

A cool thing to observe during an eclipse is the sun's image on sidewalks and flat walls where dappled sunlight is shining through a tree with leaves. The little gaps act as lenses, and the dapples have the shape of the sun. Usually they are round and nobody notices.


1 person likes this
Posted by musical
a resident of Palo Verde
on Oct 23, 2014 at 2:41 am

@Question -- all things in moderation. My 99.999% opaque (optical density 5) black polymer eclipse glasses are printed with the instruction "Use continuously for up to 3 minutes, intermittently for several hours. Do not use after eye surgery or with diseased eyes. This device is not a toy."

The sun is a comfortable orange ball, but I don't feel a need to stare directly at it for more than 10 or 15 seconds at a time. Nothing changes too quickly from one minute to the next unless you have the magnification of a filtered telescope trying to catch the exact first tangent point of the moon eclipsing the sun, which I interpolate to around 1:52:49pm PDT for Palo Alto.

Turns out the moon will cover exactly 50% of the sun's diameter at the 3:15 maximum, which amounts to around 40% in area, as the article indicates. (Interesting geometry problem for the mathematically inclined high schooler.)

Current weather forecast for the afternoon is partly cloudy and clearing.


Like this comment
Posted by Question
a resident of Another Palo Alto neighborhood
on Oct 23, 2014 at 5:02 pm

We went to the Foothill event. It was awesome! There was a giant sun spot in the middle of the sun, and it was visible with even the eclipse glasses. The big telescope lets you even see hot eruptions from the sun's surface. Very cool.

I heard thenext solar eclipse will be in 2017, but it will be very early in the day on the west coast. I don't know if this will be a problem. I'm told it will be like 90% total from here.


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