CSUN’s Solar System : Science: Unlike many of their peers, astronomers at the college’s observatory work in the daytime. They study only the sun.

Many astronomers are professional night owls, going to work after sundown to gulp coffee and train their telescopes on stars, planets and other celestial bodies best viewed in the dark.

But Gary Chapman, a professor of astronomy and physics at Cal State Northridge, goes to work in the bright light of morning. In fact, he can’t even do his job at night.

Why? He follows the sun.

Chapman is director of a small observatory operated by the university that studies the sun exclusively. Located in a remote area west of Sylmar, the main building looks like a lunar lander in an old sci-fi movie: an egg-shaped dome atop four spindly-looking struts.

There, Chapman and a team of astronomers, students and technicians are investigating one of the least-understood of solar phenomena: sunspots. The answers they seek may have a bearing on how the human race can protect itself against the potentially devastating warming of the Earth known as the “greenhouse effect.”

First observed by Chinese sky-watchers thousands of years ago, sunspots are dark blemishes that are mysteriously cooler than the rest of the sun’s surface. While solar temperatures average more than 10,000 degrees Fahrenheit, sunspots are about 4,000 degrees cooler.

Scientists believe the spots are caused by undulating coils of magnetic force--”magnetic ropes,” Chapman calls them--that twist and turn in the thermonuclear reactor of the sun’s roiling interior. When the ends of these little-understood coils hit the surface, sunspots appear, he says.

Sharp increases in the number of sunspots can have significant impacts on the Earth. They produce solar flares, massive bursts of radiation and energy that are hurled into space with the force of thousands of exploding hydrogen bombs.

The flares create a sort of cosmic poltergeist effect, reminding earth-dwellers of the sun’s awesome power. Electrical power fails, radio and navigation signals are disrupted, Earth-orbiting satellites obey commands never sent. The flares also ignite vivid, multicolored streamers of light in the night skies over the far north known as the aurora borealis.

Sunspots wax and wane in a mysterious cycle that peaks every 11 years or so. The last “solar maximum” occurred from 1989 to 1991. In March, 1989, a burst of sunspots knocked out power in Quebec, scrambled satellite communications and tripped a radiation alarm aboard a supersonic Concorde jet flying near the North Pole.

For many years, Chapman said, the conventional scientific wisdom held that since sunspots are cooler than the rest of the sun, its energy output fell when they popped up in large numbers.

Paradoxically, astronomers have since discovered the opposite is true: Heavy sunspot activity actually increases the sun’s heat. Why? That’s a question that Chapman and other astronomers are studying intensively.

Although temperature changes on the sun increase or decrease the amount of heat that the Earth receives only by a fraction of a percent, such fluctuations, over a long period, could have major implications for this planet’s climate, Chapman said.

Chapman and other astronomers believe, for instance, that a sudden and unexplained disappearance of sunspots may have been responsible, at least in part, for a period of unusually harsh winters in Europe stretching from about 1500 to 1850.

The period, known as the “Little Ice Age,” saw some dramatic climatic changes. People starved when wheat crops failed in Poland. Glaciers ground into Swiss valleys faster than anyone could remember. Dutch canals that normally were navigable all winter froze over.

“There are several paintings of Rembrandt, for example, that show ice skaters on the canals in Holland. It never gets that cold in Holland anymore,” said Stephen Walton, another Cal State Northridge professor who performs sophisticated computer analyses of solar data at the observatory’s equipment-jammed headquarters shack.

“I grew up in New Jersey and I don’t remember the details, but there was . . . either an attack on New York City or a retreat from New York City during the American Revolutionary War, in which the troops marched across the Hudson River. It was frozen, shore to shore. And again, it just doesn’t get that cold in the winter anymore.”

At the moment, Chapman is trying to find out if there are correlations between changes in the sun’s magnetic fields and variations in its heat output.

The sun’s output, also known as its brilliance, is important because it may help scientists better understand the greenhouse effect, which some scientists contend--in a theory that is still debated--is slowly warming the Earth. The theory holds that increasing amounts of heat generated by sunlight are being trapped in the atmosphere, partly because of changes to the atmosphere caused by artificial gases.

If scientists can measure the sun’s output more precisely, they can subtract increased solar energy from the amount of warming caused by humanity. The result could lead to better strategies for reducing any human activities that contribute to global warming.

“If the sun’s increased output warms the Earth, and if man’s effects are warming the Earth, we need to disentangle those two,” he said.

Cal State Northridge’s little observatory lies at the end of a dirt road that winds through brushy land crisscrossed by aqueducts and power lines of the Los Angeles Department of Water and Power, just north of the Los Angeles Reservoir.

Its most distinctive features are two gleaming white telescope domes known simply as Big Dome and Little Dome. Big Dome, which resembles a lunar lander, holds the largest telescope--a 15-foot-long tube with a 24-inch lens. According to Chapman, it is one of the two biggest solar telescopes run by a U. S. university (the other is used by Cal Tech at its Big Bear observatory).

So delicate are its optics that staffers clean the exterior glass not with a dust cloth but by spraying it with a thin plastic film. Dust particles get peeled away with the film. The telescope’s interior is a vacuum, because the heat from trapped air could warp metal components.

One day last week, Chapman--an affable man with a white beard who wears an Indiana Jones-style felt hat--climbed a circular staircase into Big Dome’s belly. There he pushed a button and watched as its spherical top split open, with a clank and a hum, and exposed the scope to a brilliant noontime sky.

As sunlight poured down, Chapman donned dark-tinted goggles and peered at a blazingly white image of the sun that appeared on a viewing screen. Near the solar equator lay a single dark spot.

“See that little one? That’s one or two Earths,” said Chapman, commenting on the actual hugeness of the spots, which only look small on the sun because its mass is a million times greater than the earth.

While nighttime astronomers seek out mountaintops and clear skies for their work, Chapman and his cohorts delight in their observatory’s low-lying location in the often smoggy east San Fernando Valley. While it disgusts other local residents, smog means better viewing for the astronomers.

That’s because smog’s presence indicates an inversion layer: cooler air that slips into the Valley off the Pacific Ocean and hugs the ground. Although the inversion traps masses of stagnant, brownish air, it replaces hotter air that normally rises and can produce heat shimmers that distort the sun’s image when viewed through a telescope. Heavy smog can force a shutdown in observations but usually it merely acts as a mild filter.

On days when winds push out the smog, “you can get a nice suntan, but the viewing conditions are sometimes terrible,” said Chapman, explaining that winds make the telescope tube vibrate annoyingly.

Cal State Northridge has operated the observatory since 1976, after it was donated by The Aerospace Corp., a nonprofit research firm in El Segundo that built the facility under contract to the Air Force in 1969.

At the time, Air Force officials wanted to put a manned space station into orbit and needed data on possible harmful effects on astronauts from X-rays, ultraviolet light and other emissions from the sun.

When the proposed station’s high price tag caused the Air Force to lose interest, The Aerospace Corp. turned the solar observatory over to the university for a token $1, Chapman said.

In addition to the faculty members who use it, the $150,000-a-year observatory is used by a rotating cast of a dozen undergraduate and graduate students who, among other things, monitor day-to-day digital information gathered by Little Dome telescopes.

The Big Dome scope is used primarily by Chapman and others trying to penetrate the mysteries of the sun’s magnetic fields.

Last month, two other CSUN professors, John Lawrence and Cristina Cadavid, presented a paper before a panel of the American Astrophysical Union that used data on large solar magnetic fields to predict the behavior of fields that are closer together. That information, Cadavid said, may help astronomers design computer models that will lead to better understanding of such fields.

But professors and students aren’t the only people drawn to the observatory. Its futuristic looks have attracted a number of movie and television producers who have used it as a backdrop.

The observatory appeared in the opening scenes of Woody Allen’s “Sleeper,” as well as a number of installments of the CBS science series “In Search Of . . ., “ hosted by Leonard Nimoy.

It also turned up in a movie called “Galaxina,” a forgettable sci-fi tale about a group of futuristic bikers who terrorize an ex-Playboy centerfold lashed to one of Big Dome’s struts.

“I don’t even want to talk about that one,” sighed Chapman.