Since 16 March 1999. Updated 11 August 1999.


Safe Ways to See a Partial Solar Eclipse

You can see the event with a solar filter. Only filter that should be used for visual observations of the partial phases of an eclipse are those designed for visual observing of the Sun.

Visual observation of the projected image is the simplest and least expensive way for observing. Poke a small hole in an index card with a pencil point and hold a second card two or three feet behind it. The hole will project a small, inverted image of the Sun's disk onto the lower card. A large hole makes the image bright but fuzzy, a small hole makes it dim but sharp. By enclose this set up in a box to keep out as much daylight as possible, you can use a tiny pinhole (perhaps in aluminum foil) for a nice, sharp image.

A leafy tree; natural pinhole projectors
A leafy tree can produces the Sun's disk like a pinhole. Watch the dappled ground in the shadow of a tree for swarms of crescents instead of the usual round Sun disks.

Pinhole mirror
For indoor classroom observing, cover a pocket mirror with a piece of paper that has a 1/4 inch hole pencil in it. Open a window and places the cover mirror on the sunlit sill so it reflects a spot of light onto the far wall inside. The spot of light is an image of the Sun's face. The farther away the wall is the better; the image will be only one inch across for every 9 feet from the mirror. Also, the Sun's image can be projected through a pair of binoculars or small telescope onto a piece of paper.

Photography of the projected image
The projected image can be photographed with a camera or video equipment. This might be a technique or choice for someone with a camera that can not use a telescope or telephoto lens. When Baily's beads occur, projected image of the event also appear on the paper.

Observing Tips and Suggestion
The following are offered based on experiences with eclipse observing

1. Practice observing beforehand. This means to set up the equipment readily.

2. To choose a right exposure for your filter, do a dry run on the uneclipsed day at least a couple of week beforehand.

3. Try a wide variety of exposure, select a best, and use that exposure throughout the partial eclipse going on. When the Sun is very thin, increase the exposure both due to limb darkening on the solar rim. Don't forget to take an uneclipsed Sun before and after the event.

4. Make arrangements for your observing site before the eclipse day.

5. Protect your equipments for the Sun's heat and be prepared to cover it in the unexpected event of rain.

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