I won my first telescope when I was nine years old by selling 500 boxes of flower seeds door-to-door. (I was a good talker even then.) It wasn't much of an instrument, just a four-inch refractor that suffered from what astronomers call chromatic aberration: it focused different colors at slightly different distances, so that only one color could be in focus at a time. Stars and planets were so blurred that I almost relegated the telescope to my closet. But it was saved by its sun filter, which allowed a smidgen of the sun's green light to pass through. I gasped out loud the first time I used it. Limited to just one color, the solar disk came in razor-sharp, and sunspots appeared like large black islands in a vast emerald sea.
That experience inspired my first amateur research project. Every day that summer at precisely 11:00 A.M., I set up my telescope and carefully sketched the sunspots on a piece of graph paper. I quickly discovered that the sun's surface, unlike the earth's, rotates at different rates depending on latitude. Sadly, my intensive investigations soon wore out the scrawny scope. Since then, I've visited our home star mostly through no. 14 welder's glass duct-taped over binoculars and recently via the World Wide Web.
Image: Daniels and Daniels
Because the solar image can be easily viewed in daylight by many people at once, Hegerberg's fabulous device is perfect for eclipse watching. Moreover, by presenting such enticing images during the day when it is easiest to reach nonastronomers, this projector could revolutionize sidewalk astronomy--the time-honored practice whereby amateur astronomers set up small telescopes to give passersby a peek at the heavens.
Hegerberg fashioned his first solar projector, the "Sun Gun," from an inexpensive telescope assembly, some PVC piping and a large flowerpot. Those interested in the details should check out his Web site. Here I will describe his second-generation device, the "Sun of a Gun," which can be quickly and cheaply assembled from a paint bucket. If your telescope has a heliostatic (sun-following) motor drive, you'll be able to track the sun's motion for hands-free viewing.
You'll need a plastic five-gallon (20-liter) paint bucket (such as Home Depot part no. 084305355553). Discard the lid and paint the inside of the bucket black to prevent ambient light from coming through the translucent plastic. Cut a 21/4-inch hole in the bottom using a hole saw attached to an electric hand drill. Through the hole, thread a male flexible adapter for a water hose (Ace Hardware part no. 45708) and secure it in place with one two-inch conduit locknut (Home Depot part no. 051411461966). (Obviously, readers outside the U.S. will need to adapt these measurements to a metric equivalent, depending on the availability of hardware.)
Next, drill an 1/8-inch hole about a half-inch from the end of the adapter. Line up this hole with the screw hole in the eyepiece assembly and lock the two together using the screw that normally holds the eyepiece in place. If the adapter does not fit your scope, affix a universal camera adapter (about $30 from Orion Telescopes; 800-676-1343) to your scope and attach the bucket to that