BBC

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

Giant sunspot may explode

The Sun is unusually spotty at the moment

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.

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.

Bigger than earth

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'

Bigger than the earth

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.

-- Anonymous, March 29, 2001

Answers

Damn... where did I put my suntan oil?

-- Anonymous, March 29, 2001

Arrrghhh -- when this cycle got rolling I was asking around work for access to an ancient old lead-lined safe that I remembered seeing. Wanted somewhere electromanetically insulated to store my backup tapes in.

The few I asked I guess became even more sure that I was losing it. Never did get access to that safe either.

Guess we may see if the utilities learned all they think they did from that Ontario outage in 1988.

R

-- Anonymous, March 29, 2001

How long does it take for flares to reach earth? I'm vaguely recalling 2 or 3 days.

-- Anonymous, March 29, 2001

Dunno. Who was it who knew all about sunspot activity?

-- Anonymous, March 29, 2001

Just popped an X1.7, nothing to get really excited about... CME was fast moving, so should be here in 2 days (normally takes 3)....

This one has X10+ megaflare potential... that's the one I'm drooling for....

-- Anonymous, March 29, 2001

Why Carl, that's the first time I've thought of "Sky and Telescope" being a stroke book... ;)

-- Anonymous, March 29, 2001

Hey, I'd get my cookies seeing one of these over Southern California!

CNN story today

-- Anonymous, March 29, 2001

See Spot. See Spot. Run. Run from Spot. Run.

-- Anonymous, March 29, 2001

I've only seen the northern lights once, but it was utterly awe- inspiring. I remember being up on the hill standing in the snow, watching the green ribbons twisting over the mountains. Stunning.

-- Anonymous, March 29, 2001

Comment added at 17:36 UT: The halo CME mentioned above showed extremely rapid expansion and was visible in LASCO C2 images already at 10:26 UT. The CME will impact Earth, perhaps as early as between noon and midnight tomorrow March 30 and cause solar wind speed to jump to near 1000 km/sec. Very severe geomagnetic storming is possible.

Region 9393 has, in addition to the X class flare, produced 6 M flares today, 4 of them within an interval of only 59 minutes!

-- Anonymous, March 29, 2001

New solar flare erupts Thursday, 29 March 2001 21:49 (ET)

New solar flare erupts

BOULDER, Colo., March 29 (UPI) -- A major solar flare erupted Thursday at 5:15 am EST from the largest sunspot area observed in a decade, according to the National Oceanic and Atmospheric Administration.

A strong radio blackout followed the burst, officials said, although geomagnetic storms are expected to be minor and isolated.

Barbara McGehan, a spokeswoman for the NOAA Space Environment Center in Boulder told United Press International that observers have been watching the sunspot area for several weeks, detecting increased activity and expecting a flare.

"But because of the size of the sunspot, they're expecting more. This is unlikely to be the only one," she said.

She added that Thursday's flare-up is not what she would consider an extreme event, explaining, the sun's activity cycle is around solar maximum.

However, "the sunspot cycle was basically past maximum, so we were surprised," Carsten Denker, a solar observation scientist with the national Big Bear Solar Observatory in Big Bear, Calif., told UPI.

The sunspot that spawned the flare was nonetheless of great interest to the Big Bear observatory and to other solar observatories around the world, even though it was less than one week old, he said.

"It had the intensity, size and polarity to create a big one, but because the cycle was on the wane, it wasn't expected. It's like a short circuit. The energy is suddenly released. But we expected more of these sooner," he sad.

Similar to earthquakes, the magnitude of solar flares in measured in multiple units. For solar flares, the smallest are M-class flares and the largest are X-class flares, and each one is measured on a sliding scale of intensity based on a set mathematical formula.

Thursday's flare was categorized as a X-10 flare, Denker explained. The largest flare in the past two years was an X-20.

"It's still a pretty big sized flare," he commented, "and there's still a chance for more flares, but I doubt if any will approach this size."

(Reported by UPI Science Writer Kurt Samson in Washington.) -- Copyright 2001 by United Press International. All rights reserved.

-- Anonymous, March 30, 2001

It was not an X-10, it was an X-1.7... huge difference... there has been no X-10 in recorded history, and if there had been an X-20, there would not be any history to record :lol

-- Anonymous, March 30, 2001

Solar Flare Eruptions May Disrupt By Joseph B. Verrengia AP Science Writer Friday, March 30, 2001; 3:40 p.m. EST

BOULDER, Colo. –– Telecommunications may be disrupted briefly and the northerly night skies will shimmer red and green this weekend as intense storms rage on the sun, scientists say.

The biggest sunspot cluster seen in at least 10 years has developed on the upper right face of the sun's disc, according to satellite readings. Researchers said the sunspot could persist for several days.

The sunspot, which is a cooler, darker region on the sun's surface, is caused by temporarily distorted magnetic fields. It spawns tremendous eruptions, or flares, into the sun's atmosphere and hurls clouds of electrified gas toward Earth.

NASA scientists said the most powerful flare erupted Thursday, rated a class X, the most potent category. The other flares were less intense.

The eruptions triggered a powerful, but brief, blackout Friday on some high-frequency radio channels and low-frequency navigational signals, scientists said. They forecast at least a 30 percent chance of continuing disruptions through Sunday.

The solar activity is also expected to produce an aurora in the night sky over northern latitudes. The colorful, shimmering glow occurs when the energetic particles strike the Earth's upper atmosphere.

In addition to radio disruptions, the charged particles can bombard satellites and orbiting spacecraft and, in rare cases, damage industrial equipment on the ground, including power generators and pipelines.

-- Anonymous, March 30, 2001

Oops, Maggie, I made a mistake... that Thursday flare was just an X1.7... however, I thought the scale after the first X1-10 level, continued in increments of one. After Monday's flare, I see the increment changes to 10's after the X10 level, so what I was figuring an X20 would be by that scale is an X100...

So when the chart was reading X18 Monday, I thought it should have been an X10.8 ....

Sorry, my 2 cents was just that, 2 cents :)

-- Anonymous, April 04, 2001