Saturn's Rings from San Pasqual Park in Escondido

"Some people think they're looking at a video and think that it's fake," says Bob Nanz, the San Diego Astronomy Association's North County coordinator. "Especially Saturn, because you can really see the rings. I say, 'We're honestly not going to set up this big telescope just to trick you. '" On Saturday, May 6, the California Department of Parks and Recreation will host an Astronomy Day celebration at San Pasqual Battlefield State Historic Park. "We have three telescopes and a solar telescope out there right now, but we're relying on volunteers [from organizations] like San Diego Astronomy Association to bring out their equipment too," says Curt Lawrence, astronomy outreach program coordinator for the San Pasqual park.

For Astronomy Day, the park's community room will be set up with computers loaded with interactive software containing general astronomy information geared towards children. Outside, visitors can peer through telescopes -- in the afternoon, when the sun is still high in the sky.

"There are two types of solar telescope," explains Nanz. "One has a filter you place in front of a [regular telescope], which lets you see sunspots and the H-Alpha." According to wikipedia.org, H-Alpha (the h stands for hydrogen) is a wavelength visible in the red part of the electromagnetic spectrum.

When seen through an H-Alpha telescope, sunspots (areas at over one million degrees Celsius believed to contribute to solar flares) appear as dark splotches on the sun's surface. A solar flare is defined as "a violent explosion in the sun's atmosphere, with an energy equivalent to tens of millions of hydrogen bombs." Through the telescope these projections of fiery plasma look like lines and swirls shooting from the sunspots.

Even with a filter, attempting to view the sun directly through a telescope can cause blindness. The second type of solar telescope has mirrors inside that redirect the light path, offering an indirect view of the sun. But, Nanz warns, redirected sunlight isn't necessarily safe either. His Dobsonian telescope, which weighs over 200 pounds and utilizes a 25-inch diameter mirror, includes a warning to the user to keep the telescope away from flammable objects after removing the cap. "I left it next to my car once, and it burnt the side-view mirror," says Nanz.

One popular type of telescope for stargazing at night is the refractor, a simple scope that has a lens at one end and an eyepiece at the other. "Those are small and easy to use," says Nanz. "The Schmidt-Cassegrain is [another popular telescope]; it's relatively small, has a very short tube, and 'folded optics' -- the tube is only two feet long, but the actual telescope acts like it's ten feet long." This telescope combines mirrors and lenses to form an image.

"It's really interesting when I get a bunch of inner-city middle schoolers, and they're all talking tough, and they've got their cell phones, but when they look through the telescope and see the rings of Saturn for the first time, you can hear a pin drop," says Lawrence. "That's the real kick I get. Then you can't get them away from the telescope. They're, like, 'Wow, that planet's really green,' and then the questions start: 'How far away is that? How big is that?' The sun looks like a golf ball, but you could span 3000 Earths inside that sun. When you see a flare, it could be going out 80,000 miles into the sky -- that's two Earths!"

Nanz's large telescope cost "somewhere in the $10,000 to $15,000 range." Lawrence insists, "You don't need a lot of money to get into [the hobby of astronomy]. Just buy a pair of binoculars and look up."

On May 6, amateur astronomers should be able to see Saturn, the first-quarter moon, and Jupiter through binoculars. -- Barbarella

Astronomy Day

Saturday, May 6, 1 p.m. to 9 p.m.

San Pasqual Battlefield State Historic Park

16666 San Pasqual Valley Road

(1.5 miles east of San Diego Wild Animal Park)

Escondido

Cost: Free

Info: 760-737-2698 or parks.ca.gov/events