The Rarest Eclipse Transit of Venus Exploratorium

How Do You View It?

OPTICAL PROJECTION

You MUST take precautions to protect your eyes from permanent damage caused by looking at the Sun with the naked eye or with any optical device. Projecting the Sun's image is a good alternative. The usual way that you are told to view the Sun is by building a pinhole projector. Unfortunately, this method probably won't work for the transit of Venus. Pinhole images are pretty dim and small. They also lack the proper resolution to view the tiny disk of Venus. But there's another projection method that uses a pair of binoculars.
DO NOT LOOK THROUGH THE BINOCULARS!

Exploratorium TV 2 player


Photos showing how to view the transit safely(1) First, you should firmly fix the binoculars to a tripod. You can do this with duct tape (what else?).

(2) Make a shield with a piece of cardboard. Trace circles around the front lenses of the binoculars and cut out the circles. Put the front lenses of the binoculars through the holes you cut and tape the shield to the front of the binoculars.

(3) Put the lens cap over one of the large binocular lenses or tape over one of the front lenses with duct tape. (You really only need a monocular for this.)

(4) Use the duct tape to seal any holes that leak light past the cardboard.

(5) Point the binoculars towards the Sun while holding a piece of white cardboard about a foot behind the eyepiece.

(6) It will take a little effort to find the image of the Sun. Once you do, you can focus the binoculars to create a sharp image of the Sun.

Be careful not to put your hand or anything flammable near the eyepiece! The concentrated sunlight exiting there can cause a nasty burn or set something ablaze!

Now you can watch a beautiful, bright, magnified image of the Sun as the transit proceeds. You will have to adjust the tripod to account for the Earth's rotation. One possible warning here: You might give your binoculars a cooling break now and then. The eyepiece can become overheated and the lens elements may separate if you leave it focused on the Sun too long. You've been warned!



FILTERS

If you feel that you just have to look directly at the Sun, be absolutely sure that you have the correct filter. Just because a filter makes the Sun seem dim does not mean that it's blocking invisible infrared or ultraviolet radiation that will certainly cause eye damage in short order.

Do not use sunglasses, Polaroid filters, smoked glass, exposed color film, X-ray film, or photographic neutral density filters.

Make sure that the supplier of your solar filter is reputable and reliable. A few are listed below. You can, for instance, look at the Sun with a number 14 welder's glass. Get this from a welding supply store. Silver-based black-and-white photographic emulsions, when exposed and developed fully, can be used if you are experienced and knowledgeable in this area. You might need several layers. It's easier, though, to spend a couple of bucks on a filter you know is safe.

Unless you're quite knowledgeable and experienced, it's much safer not to use a telescope to watch the transit. However, if you choose to use a telescope, only use the filter supplied by the manufacturer or by a manufacturer who makes a filter specifically for the instrument you are using. In some cases though, even this is bad advice (see the solar filter below.)

The suppliers of some cheap refractor telescopes supply a welder's glass filter (pictured left) that screws on to the eyepiece.

DO NOT USE THIS TYPE OF TELESCOPE FILTER!

They may heat up and crack as you are looking through the telescope. A proper solar filter always goes on the front end of the telescope, blocking the sunlight before it enters the optical system.

Thanks to the Orion Telescope Center for the loan of this unsafe filter. Orion does not sell these! They just had one around as a bad example. They are good and knowledgeable people.

By following the instructions above and using a modicum of good sense, you will be able to enjoy transits and solar eclipses.

Suppliers of Filters and Eclipse Glasses

Celestron International, 2835 Columbia St., Torrance, CA 90503. (310) 328-9560

Meade Instruments Corporation, 16542 Millikan Ave., Irvine, CA 92714. (714) 756-2291

Orion Telescope Center, 3609 Buchanan St., San Francisco, CA 94123. (415) 931-9966

Rainbow Symphony, Inc., 6860 Canby Ave. #120, Reseda, CA 91335. (818) 708-8400