May 9 Partial Solar Eclipse

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There is a partial solar eclipse over the Hawaiian Islands on Thursday May 9, from 2:23 – 5:01 p.m.  This provides an overview of the event and also gives guidance on safe and unsafe viewing techniques.

Hawai‘i is only US state to see May 9 partial solar eclipse!

On Thursday, May 9, Hawaii will be the only state to see the first solar eclipse of 2013. At the peak of the eclipse, at 3:48 p.m., a viewer using a safe filter will see 44 per cent of the sun blocked by the moon. As seen from Honolulu, the eclipse on May 9 will start at 2:23 p.m. as the moon starts to slide across the solar disk. The “bite” will get bigger and bigger till the peak at 3:48 p.m., with well over a third of the sun blocked by the moon. After that, the moon will slowly uncover the sun, the ‘bite’ will get smaller and smaller, and the partial eclipse will end at 5:01 p.m.

These timings will vary a little elsewhere in the islands; in Līhu‘e, Kaua‘i, for example, the eclipse stars at 2:20 p.m. and ends at 4:58 p.m. The eclipse starts in Hilo at 2:25 pm and is over at 5:04 p.m. Long story short: if you start looking by 2:19 p.m. anywhere in the islands you should be in good shape to catch the start of the eclipse.

Warning: Improper viewing of a partial solar eclipse can cause severe and permanent eye damage.  Learn to use a safe viewing technique!

The retina of your eye cannot feel pain, so you will not notice damage being done to your vision until it is too late.  “Homegrown” filters may seem to provide an image that does not look too bright in visible light and therefore are tempting to use.  However, almost all of these homegrown filters allow too much ultraviolet and infrared light to pass through.  Too much infrared light will act like an infrared heat lamp and can “cook” the retina of your inner eye quickly.  Too much ultraviolet light and the corona of your eye can cloud over.

UNSAFE VIEWING TECHNIQUES
UNSAFE: Smoked glass, no matter how dark.
UNSAFE: Exposed color film, no matter how many layers
UNSAFE: Multiple pairs of sunglasses.
UNSAFE: Looking at the sun with the naked eye, even through layers of clouds.
UNSAFE: Looking through the viewfinder of a camera that does not have a special reflective filter. 
UNSAFE: Looking through any telescope or binoculars without professional solar filters on the front of the optics.  (Note: many small telescopes are sold with solar filters that screw into the eyepiece at the back of the camera.  These are potentially hazardous because the heat build-up inside the telescope can cause the filter to crack, resulting in the full, unfiltered light of the sun reaching your eye.  This can cause instant eye damage.)

There are several safe viewing techniques which allow anyone to experience the excitement of watching the sun as it is eclipsed by the moon.  These techniques can also be used on any clear day to see sunspots on the sun. 
These safe viewing methods include direct viewing through special solar filters and indirect solar projection.

SAFE DIRECT VIEWING TECHNIQUES
SAFE:
Come to Bishop Museum eclipse viewing event on Thursday May 9, from 2-5 pm (included in museum admission).  
About the event:

SAFE: Inexpensive hand-held solar viewing filters (“sun peeps”) are commercially available. 

NOTE: Bishop Museum has sold out of these devices as of 12 noon on Wednesday May 8.  If you have viewers from June 2012 (Transit of Venus), they should still be safe to use as long as you inspect them for scratches beforehand.  DO NOT use viewings from, say, the 1991 total solar eclipse over the islands since these viewers do decay over time.

SAFE: Special solar filters that mount on the front of a telescope are available from astronomy specialty stores.  However, these do cost several hundred dollars on up. 

SAFE INDIRECT PROJECTION TECHNIQUES

NOTE: Projection techniques focus an image of the sun onto a piece of white paper, where it can be safely viewed by anyone nearby.  Using these techniques, you will be looking down at a piece of paper, not looking directly at the sun.

SAFE: The spot mirror projection technique.  Cover a small mirror (a plain hand mirror works fine) with a sheet of paper that has a dime-sized hole cut in the center.  Tape the sheet of paper to the mirror.
Bounce the image of the sun onto a sheet of white paper 30 – 40 feet away.  The darker the screen area is, the better the image shows up.  Here, we’ve found that a tipped-over garbage can makes a great shady area to project the image into.
If you are using a mirror with a handle, you can stick the mirror in a bucket of sand to hold it, rather than having to hand-hold the mirror yourself.

SAFE: Another safe technique, if carefully monitored by an adult at all times, is binocular projection.  Into a sheet of cardboard, cut a single round hole just big enough to fit over one of the large lenses of a pair of binoculars.  Put the binoculars with this cardboard mask on a tripod or prop them against something steady like a chair.  Place a sheet of white paper to act as a projection screen 2 to 3 feet behind the binoculars in the shade of the cardboard mask.  WITHOUT LOOKING THROUGH THE BINOCULARS, point the big end of the binoculars at the sun and move them around a bit into a flash of white light can be seen on the paper.  Once you get an image of the sun on the paper move the paper in or out and adjust the focus knob on the binoculars to produce a clear and sharp image of the sun.

DO NOT PUT YOUR EYE UP TO THE BINOCULARS AND KEEP OTHERS AWAY ALSO.  IF ANYONE LOOKS AT BINOCULARS AIMED AT THE SUN, INSTANT EYE DAMAGE WILL OCCUR.  BE AWARE THAT IT CAN BE A REAL TEMPTATION FOR CHILDREN TO GO UP TO BINOCULARS AND LOOK THROUGH THEM WHEN ADULTS ARE NOT WATCHING.  IF YOU INTENT TO USE THIS METHOD, YOU MUST KEEP A CONTINOUS LOOK-OUT!

Safe: Telescope projection.  Follow the same instructions as provided for binocular projection above.  THE SAME WARNINGS APPLY: NEVER LOOK THROUGH A TELESCOPE WHEN IT IS POINTED AT THE SUN.  DON’T FORGET TO LEAVE THE CAP ON, OR COVER, THE SMALL VIEWFINDER (SPOTTING SCOPE) LOCATED ON THE SIDE OF THE MAIN TELESCOPE.  LOOKING THROUGH THE SMALL TELESCOPE WILL ALSO CAUSE EYE DAMAGE.

Safe Viewing Technique

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