Scientists learn what makes Northern Lights flare

The multicolored aurora borealis and aurora australis -- the Northern Lights and Southern Lights -- represent some of Earth's most dazzling natural displays.

Now scientists using data from five NASA satellites have learned what causes frequent auroral flare-ups that make this green, red and purple light show that shimmers above Earth's northernmost and southernmost regions even more spectacular.

Writing in the journal Science, the scientists said on Thursday that explosions of magnetic energy occurring a third of the way between Earth and the moon drive the sudden brightening of the Northern Lights and Southern Lights.

There had been debate among scientists dating back decades about what triggers these auroral flare-ups.

The findings from the THEMIS satellites and a network of 20 ground observatories in Canada and Alaska confirmed that it is due to a process called "magnetic reconnection." THEMIS stands for Time History of Events and Macroscale Interactions during Substorms mission.

Auroral displays are associated with the solar wind -- electrically charged particles continuously spewing outward from the sun. Earth's magnetic field lines reach far out into space as they store energy from the solar wind.

The researchers said that as two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the lines reconnect, causing magnetic energy to be turned into kinetic energy and heat. The release of this energy sparks the auroral flare-ups.

"We showed that the process begins far from Earth first and propagates Earthward later," said Vassilis Angelopoulos of the University of California at Los Angeles, who led the research.

The moon is located about 240,000 miles from Earth, and this process is occurring roughly 80,000 miles from Earth.

The same mechanism causing the auroral brightening also can cause problems for satellites, power grids and communications systems on Earth and could endanger astronauts in space, the researchers said.

Biologists aim to wipe out "Rat Island"

Two centuries after rats first landed on a remote Aleutian island from a shipwreck, wildlife managers in Alaska are plotting how to evict the non-native rodent from the island that bears their name.

Rat Island, like many other treeless, volcanic islands in the 1,000-mile (1,609-km) long Aleutian chain, is infested with rats that have proved devastating to wild birds that build nests in the earth or in rocky cliffs.

"They pretty much made the island worthless for a lot of wildlife," said Art Sowls, a biologist with the Alaska Maritime National Wildlife Refuge, which sprawls across the Aleutians and other Alaska islands.

Rodents have reigned at Rat Island at the western end of the Aleutians since the 1780 shipwreck of a Japanese sailing ship, wreaking havoc on millions of seabirds with no natural defenses against land predators.

The U.S. Fish and Wildlife Service, which manages the Maritime refuge, is drawing up plans to wipe out Rat Island's rats. A formal proposal is expected in about a month, according to Sowls.

The agency is trying to find an effective way to wipe out rat populations without harming other wildlife. Rat Island is a good starting point, according to biologists, for a removal program because it is small without much other wildlife. Rats are a problem shared by remote islands all around the world. Biologists said successful rat removal programs have taken place in more than 250 islands including Campbell Island south of New Zealand and Langara Island in British Columbia.

"A lot of people go, 'Oh they're just rats, what's the big deal?'Once informed about the environmental destruction wrought by rats, citizens are generally determined to avoid them. Rats are blamed for causing about half the extinctions of various species worldwide since the 1600s and are persistent nuisances once established, said Clarke.," said Ron Clarke, assistant wildlife conservation director at the Department of Fish and Game.

"They're very good swimmers. They'll eat anything. They're just very good at surviving," Clarke said.

SWEEPING RAT MANDATES

Alaska state officials have issued sweeping new regulations that slap rat-prevention mandates on Alaska ports and harbors that have served as entry points for invading rodents. The removal plan and new state regulations are extensions of previous anti-rat policies in Alaska.

Since the early 1990s, wildlife refuge managers have maintained a "rat-spill" program -- in which emergency responders prevent the spread of rats from shipwrecks -- similar to oil-spill contingency plans maintained by state and federal agencies.

"It's entirely possible that in a shipwreck situation, the environmental damage created by the introduction of rats into the environment would be even worse than that of a major oil spill," Sowls said.

He cited the situation on the Aleutian island of Kiska, which still holds a colony of millions of auklets, a small seabird, but where introduced rats are decimating that natural population.

Researchers commonly find vast stretches on Kiska with no live birds, only rotting bodies stuffed into burrows. "A lot of the birds you find, the only parts the rats eat are the eyeballs and the brains," Sowls said. "It looks like, unless something is done in the next 20 to 40 years, that the rats will probably eliminate that colony."