As the tropical sun blazed overhead, Curtis Roelle stood surrounded by his cameras and telescopes in the cactus garden near a Mexican beach and watched the cone-shaped shadow of the moon sweep toward him at more than a mile a second.
Tonight at 8 p.m., Mr. Roelle, 33, will show a series of slides he snapped of the spectacular total solar eclipse July 11, making him the first amateur astronomer to give a talk at the monthly open house staged by the Space Telescope Science Institute.
The droll and seemingly unflappable computer engineer, who lives in Westminster, admits being a bit awe-struck, but he nevertheless took a series of crisp pictures of the event, the longest total eclipse expected until 2132.
He had a tape recorder running, planning to make comments that he could later incorporate into slide lectures. But he was so dazzled that he forgot the tape was running, and all it picked up was a few astonished mutterings: "This is better than I expected!" "Oh! Look at that! Do you see that?"
Like thousands of other amateur stargazers, Mr. Roelle, president of the Westminster Astronomical Society, and his wife, Cheryl, flew to the arid Baja California peninsula to practice science on a small scale, for the love of it.
The Space Telescope Institute, on the campus of the Johns Hopkins University, is a center for large-scale science, controlling experiments performed by the Hubble Space Telescope. The first Tuesday of each month, the institute throws its doors open to the public for talks by experts in their fields.
The institute has always tried to find room for the non-professional. "We certainly have a kinship with amateurs," said Ray Villard, a spokesman for the institute.
Five amateur astronomers have designed experiments for the Hubble. But because of the flaw in the telescope's main mirror and other technical problems, one has been canceled and four postponed.
Mr. Roelle thinks it fitting that he will be bringing slides shot with his oatmeal box-sized telescope to the institute, which controls the 94.5-inch space-based Hubble, one of the most costly and complex scientific instruments ever created.
"The whole idea is to appreciate nature," he said.
He and his wife arrived at San Jose Del Cabo six days before the eclipse, lugging three 35mm cameras, a pair of binoculars and a 4-inch Schmidt-Cassegrain design telescope equipped with a special metallic filter to keep direct sunlight from obliterating his film.
After scouting out locations by taxi, the couple decided on the hotel cactus garden, where they set up on the Thursday morning of the eclipse. "It looked like a thunderstorm approaching," he said. "The only catch was that the dark sky was perfectly clear . . . It was a very eerie sensation."
For 6 minutes and 18 seconds, there was total darkness overhead while the horizon was rimmed with twilight.
Mr. Roelle's slides captured the image of a black disk surrounded by a halo of white light laced with what appear to be tiny filaments of red flame. Those filaments are actually huge solar prominences, condensed clouds of hydrogen gas slightly cooler than the sun's surface that are twisted by magnetic fields and thrown tens of thousands of miles out into space.
Tonight he expects to talk more about what the eclipse looked like than about the scientific aspects of the spectacle. "I'm still working on exactly how to describe it," he said last week.
Mr. Roelle recalls how he was born a few hours before the Soviet Union launched Sputnik, the first man-made satellite, Oct. 4, 1957. As a boy in Lincoln, Neb., he daydreamed about being an astronaut and later toyed with the idea of becoming an astronomer.
But he prefers his amateur status. "It seems like in a lot of professions you're required to specialize," he said. "Being an amateur, you can call your own shots, pursue your own interests."
His parents bought him his first telescope from K mart. Six months later, he used money saved from his paper route to buy a 6-inch reflecting telescope, which he used until 1980.
After receiving a degree in engineering, he went on to work as a software engineer for various aerospace companies. He is now a contract employee at the Hopkins Applied Physics Laboratory.
In 1984, he helped found the Westminster astronomy club, now one of the largest in the state with about 70 members, he said.
The Roelles' $4,000 expedition to Mexico was just the latest in a series of astronomy-related vacations. In 1986, the couple traveled to the Peruvian Andes so that he could view the constellations found in the Southern Hemisphere.
Is Ms. Roelle an astronomy buff? "Heavens no," her husband said.
But he added that the trip to Baja California helped the Roelles understand each another better.
They met many rabid eclipse-chasers who follow solar events around the globe. For some reason, many erstwhile flower children from the 1960s flocked to Baja for the event. "She thought I was crazed," he said. "But after seeing those people, she thinks I'm pretty much mainstream now."