The sun will never set on NASA's Solar Dynamics Observatory, which will aim its cameras at our nearest star from an orbit matching the Earth's rotation after its scheduled launch Tuesday.

That will place it in constant contact with two radio antennas outside Las Cruces, N.M.

It will produce the equivalent of "a 24-hour Imax movie" of events on the sun's surface, said Scott McIntosh of the National Center for Atmospheric Research in Boulder, Colo., yielding data during its five-year mission that solar scientists will study for decades.

The Advanced Technology Solar Telescope, being planned for a mountaintop in Maui, is "more like dermatology," McIntosh said. It will provide the best resolution ever of the sun's surface and corona, and will help solar astronomers fathom the processes that create explosions on the sun's surface, affecting our communications and, quite possibly, our global climate.

McIntosh isn't directly connected to either project, but the data they produce will benefit anyone who studies the sun, he said.

"It's like the Wild West. How many frontiers can you break down at once?" he asked.

The 13-foot Advanced Technology Solar Telescope mirror will be 2 1/2 times larger and have a collecting area five times bigger than any existing solar scope, said Mark Giampapa, deputy director of the National Solar Observatory, which is building the telescope with funding from the National Science Foundation.

It will give a clear optical picture of the sun, with adaptive optics that will remove the blurring effects of atmosphere. It also will be able to observe spectroscopically, in wavelengths from near ultraviolet to far infrared.

"It's a revolutionary facility. It will rejuvenate the field," Giampapa said.

Right now, Giampapa said, the best solar telescopes can resolve an area about the size of Texas.

"We'll be looking at counties," he said - areas as small as 25 to 40 miles across.

You'd think you wouldn't need a big mirror to gather light from the sun, but when you're viewing an area that small from 93 million miles away, you need as many photons as you can capture.

For as long as we've studied the sun, we still have an incomplete understanding of what causes its cyclical eruptions. Giampapa wants to know the elements and the structure that make up its magnetic fields.

Changes in that field precede and somehow affect the solar flares, mass coronal ejections and other eruptions that release energetic particles, and increase the sun's ultraviolet and X-rays.

While there are many reasons for studying the sun, they are usually placed in three categories:

Space Weather

Radiation from the sun in its active periods can threaten astronauts and even airline passengers. It can disrupt communications. Solar flares, equal in power to millions of atomic bombs, can interfere with a variety of our economic enterprises. The spot markets for energy always rise during peak solar activity, when power grids are shut down as precautionary measures, Giampapa said.

Adding "predictive power" to those eruptions and cycles would make a valuable economic contribution, he said.

Climate change

Astronomers and atmospheric scientists have long recognized a possible link between sun cycles and the Earth's climate. The most obvious example is a period called the Maunder Minimum, a 70-year span of decreased solar activity that ended in 1715. It is known as the Little Ice Age.

The exact causes aren't understood, Giampapa said, and solar scientists are reluctant to speculate on how big a role the sun might play in global warming or cooling. The variation in solar radiation of 0.1 percent isn't enough to explain temperature fluctuations.

The interaction of charged particles in the upper atmosphere may affect cloud formation, but that also isn't fully understood.

McIntosh said the science needs to come first. "It's a wickedly nonlinear problem," he said.

Basic science

Solar astronomers study the sun because it's an interesting object, Giampapa said. "It's our nearest star."

Giampapa also conducts research on sunlike stars. Understanding how our own star works can shape the science done elsewhere in the cosmos. Understanding distant stars might yield clues to our sun's behavior.

If nothing else, Giampapa said, it will raise more questions. "The more I learn, the less I know," he said.

Contact reporter Tom Beal at 573-4159 or