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Thursday, 29 March, 2001, 12:02 GMT 13:02 UK

Giant sunspot may explode

By BBC News Online science editor Dr David Whitehouse Scientists are currently observing the largest sunspot seen on the surface of our star for more than a decade.

Researchers think it could lead to a powerful flare some time in the next day or so. If this explosive event does occur, it will liberate in just a few seconds more energy than mankind has ever used.

The sunspot group, designated Noaa 9393, was first seen a month ago when it was not nearly so large.

The Sun's rotation took it from view but when it reappeared a few days ago astronomers were amazed that it had grown so big.

Over the past 24 hours it has become unstable displaying signs that its pent-up energy is about to be explosively released.

Monster spot

The sunspot is a monster according to Joe Elrod of the US National Solar Observatory at Sacramento, California: "This is the first big one we have seen during this solar cycle," he told BBC News Online.

Noaa 9393: Bigger than the Earth Every 11 years or so the Sun goes through a peak of activity when there are more sunspots on its surface. Solar observers say that 2001 is the year of the current peak.

Noaa 9393 is so large that it is even visible to the unaided eye, though astronomers say that under no circumstances should anyone without proper protective equipment ever look towards the our star as blindness can result.

Sunspots are regions of the Sun's surface that are marginally cooler than their surroundings. They only appear dark by contrast. If they were alone they would shine brighter than an arc lamp.

The 'big one'

They are caused when intense magnetic fields rise up from below the Sun's visible surface. They then become twisted and distorted by surface motions storing up vast amounts of magnetic energy.

Eventually, the magnetic energy becomes unstable and collapses, resulting in the explosive heating of vast amounts of gas. This is when solar flares are produced.

The most intense solar flares are called "white light" flares and it is this type of event that sunspot group Noaa 9393 is expected to produce.

"We saw two small flares yesterday, and they may be the precursors to the big one," Joe Elrod said.

Scientists say that the Sun is currently going through a particularly active phase with many groups of sunspots on its surface

-- Martin Thompson (, March 30, 2001


Large sunspot may generate power problems


WASHINGTON - The biggest sunspot in a decade could disrupt satellite communications and power grids this weekend, but if the weather is clear, northern U.S. communities also will enjoy a spectacular northern-lights display.

The huge dark spot on the sun's surface - 13 times Earth's diameter - is caused by a surge in magnetic activity this week in the sun's atmosphere. A storm of magnetic particles from the surge is due to reach Earth this weekend.

Satellites orbiting Earth will be the first things affected. Some are likely to shut off, as they would in response to a surge in electrical power. That could disrupt communications, including network television broadcasts that involve satellites.

Next to be hit will be power plants, transformers and power lines. They, too, will respond as if to a power surge and may shut down. That happened in Quebec in 1989 during a powerful magnetic storm.

Since then, power companies have responded by reducing power slightly before a magnetic storm to absorb surges. Still, this weekend may be a good time to hit the computer's save button more often and to be sure the machine is turned off when not in use.

Norman Cohen, a space weather forecaster at the federal Space Environment Center in Boulder, Colo., said in an interview that he expected "a medium-grade storm" today, tomorrow and Sunday.

The northern lights, or aurora borealis, a colorful sparkling event usually seen only in Alaska and northern Canada, will move farther south as a consequence. Weather permitting, people in Michigan, Minnesota, North Dakota, Wisconsin, Washington, Idaho, Montana, New York and New England may get a good view this weekend, Cohen said.

The storms could continue into next week because the part of the sun where the spot is, just a bit above and to the right of the center, does not turn away from Earth until April 5, he said.

The sunspot is so large that if someone had proper eye protection - such as glasses approved for use during a solar eclipse - it could be seen with the naked eye. Do not try it without such protection, Cohen advised. tm?template=aprint.htm

-- Martin Thompson (, March 30, 2001.

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