Solar Science

In addition to warming rays of light, the sun also produces massive quantities of charged particles that race past the Earth. The explosions that send the particles on their way largely remain a mystery to scientists, but they are hoping for added insight from a pair of satellites launched into space a few days go.

"We are at the dawning of a new age of solar observations," Russ Howard of the Naval Research Laboratory said at a NASA news conference. "We're going to be viewing things in a new dimension for us."

While the sun's surface appears to be a calm yellow disc, it's actually an enormous and actively changing star that's altered by massive explosions of electrified gas and particles known as coronal mass ejections. While astronomers have long known of the ejections existence, studying their size and scope from the single angle provided by one satellite is difficult.

Broadside view of earth and sun

After circling once around the moon to gain speed, the satellites will head in opposite directions -- one ahead of the Earth's orbit and one behind -- to provide a view of both the earth and sun when they settle into their final positions for the two-year mission.

"The highly complicated cameras on board will make it possible to follow the explosions from the sun to the earth from two satellites at the same time," said Volker Bothmer of the University of Göttingen's Institute for Astrophysics, who is organizing German participation in NASA's STEREO project.

Short for Solar Terrestrial Relations Observatory, the "space weather" project aims to see what effects the particle ejections -- which can spread to a size of 30 million kilometers (nearly 19 million miles) -- have on the earth.

"We want to learn to understand how the solar storms are created, about their three-dimensional development between the sun and the earth and finally about their effects on the earth itself," Bothmer said.

Current satellite helpful, but not ideal

Information provided by the current satellite SOHO, created in cooperation by the Americans and the Europeans, often only gives vague clues that the particle ejections are racing toward earth, sometimes catching scientists by surprise when a wave of material washes over the planet.

"What we know today is that from a small, localized region of the sun, magnetic loops spread into very large structures within minutes and move toward earth at speeds of up to 3,000 kilometers per second (1,864 miles per second), making the ejection's period of time from sun to the earth range from a few days to a few hours," Bothmer said. "The earth is like a needle that pokes through a massive bubble gum balloon."

And like anyone who has tried to pull bubblegum out of their hair, the explosions can also have serious consequences, including destruction of electronics on orbiting satellites and even possibly knocking out electricity on earth.

At the end of the two-year, $550 million (437 million euro) project, the "behind" spacecraft will be flung completely away from Earth, and will become a satellite of the sun, while the "ahead" spacecraft will curve back to fly past the moon a second time six weeks later and then be flung out in the opposite direction.