Showing posts with label Solar Conditions. Show all posts
Showing posts with label Solar Conditions. Show all posts

Tuesday, August 03, 2010

Solar Tsunami to Strike Earth

NASA's Solar Dynamics Observatory snapped this X-ray photo of the Sun early in the morning of Sunday, August 1st. The dark arc near the top right edge of the image is a filament of plasma blasting off the surface -- part of the coronal mass ejection. The bright region is an unassociated solar flare. NASA

From FoxNews:

Earth is bracing for a cosmic tsunami Tuesday night as tons of plasma from a massive solar flare head directly toward the planet.

The Sun's surface erupted early Sunday morning, shooting a wall of ionized atoms directly at Earth, scientists say. It is expected to create a geomagnetic storm and a spectacular light show -- and it could pose a threat to satellites in orbit, as well.

"This eruption is directed right at us and is expected to get here early in the day on Aug. 4," said Leon Golub of the Harvard-Smithsonian Center for Astrophysics. "It's the first major Earth-directed eruption in quite some time."

The solar eruption, called a coronal mass ejection, was spotted by NASA's Solar Dynamics Observatory, which captures high-definition views of the sun at a variety of wavelengths. SDO was launched in February and peers deep into the layers of the sun, investigating the mysteries of its inner workings.

"We got a beautiful view of this eruption," Golub said. "And there might be more beautiful views to come if it triggers aurorae."

Views of aurorae are usually associated with Canada and Alaska, but even skywatchers in the northern U.S. mainland are being told they can look toward the north Tuesday and Wednesday evenings for rippling "curtains" of green and red light.

When a coronal mass ejection reaches Earth, solar particles stream down our planet's magnetic field lines toward the poles. In the process, the particles collide with atoms of nitrogen and oxygen in the Earth's atmosphere, which then glow, creating an effect similar to miniature neon signs.

The interaction of the solar particles with our planet's magnetic field has the potential to create geomagnetic storms, or disturbances, in Earth's magnetosphere. And while aurorae are normally visible only at high latitudes, they can light up the sky even at lower latitudes during a geomagnetic storm.

Fortunately for Earth-bound observers, the atmosphere filters out nearly all of the radiation from the solar blast. The flare shouldn't pose a health hazard, Golub told FoxNews.com.

"It's because of our atmosphere," he explained, "which absorbs the radiation, as well as the magnetic field of the Earth, which deflects any magnetic particles produced."

The radiation "almost never" makes it to ground, he noted, though pilots and passengers in airplanes may experience increased radiation levels akin to getting an X-ray.

The solar particles also could affect satellites, though scientists think that possibility is remote. Orbital Sciences Corp. believe a similar blast may have knocked its Galaxy 15 satellite permanently out of action this year.

This type of solar event has both government officials and satellite manufacturers worrying.

NASA scientists warned recently that high-energy electric pulses from the sun could cripple our electrical grid for years, causing billions in damages. In fact, the House is so concerned that the Energy and Commerce committee voted unanimously to approve a bill allocating $100 million to protect the energy grid from this rare but potentially devastating occurrence.

The sun's activity usually ebbs and flows on a fairly predictable cycle. Typically, a cycle lasts about 11 years, taking roughly 5.5 years to move from a solar minimum, a period of time when there are few sunspots, to peak at the solar maximum, during which sunspot activity is amplified.

The last solar maximum occurred in 2001. The latest minimum was particularly weak and long- lasting.

The most recent solar eruption is one of the first signs that the sun is waking up -- and heading toward another maximum.

Space.com contributed to this report.

Propagation Alert: Will it hit Earth?


On August 1, 2010, the Solar Dynamics Observatory (SDO) observed a beautiful prominence eruption that may hit Earth and cause a geomagnetic storm. As the solar cycle progresses and the Sun becomes more active there will be many more opportunities to observe the causes of space weather. Want to see what happens? Follow the event at spaceweather.com.

And from the Spaceweather website:

On August 1st, the entire Earth-facing side of the sun erupted in a tumult of activity. There was a C3-class solar flare, a solar tsunami, multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection and more.

High-latitude sky watchers should be alert for auroras tonight. One and possibly two coronal mass ejections (CMEs) are heading toward Earth, propelled by the solar eruptions of August 1st (see below). NOAA forecasters estimate a 10% chance of major geomagnetic storms and a 45% chance of at least some geomagnetic activity when the clouds arrive on August 3rd and 4th.

And finally this report from our good friend Tomas Hood

At approximately 0855 UTC on August 1, 2010, a C3.2 magnitude soft X-ray flare erupted from NOAA Active Sunspot Region 11092 (1092).

At nearly the same time, a massive filament eruption occurred. Prior to the filament's eruption, NASA's Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) instruments revealed an enormous plasma filament stretching across the sun's northern hemisphere. When the solar shock wave triggered by the C3.2-class X-ray explosion plowed through this filament, it appears to have caused the filament to erupt, sending out a huge plasma cloud (a coronal mass ejection, or CME).

A shock wave can be seen emerging from the origin of the X-ray flare and sweeping across the sun's northern hemisphere into the filament field. The impact of this shock wave may well have propelled the filament into space. The movies (see links, below) seem to support the conclusion that both eruptions, occurring together, are linked, despite the approximately 400,000 kilometer distance between the flare and the filament eruption. How can this be? While we cannot always see the magnetic field lines between solar features (magnetic field lines are not visible unless there is plasma trapped along these field lines), we can assume from this event
that huge connecting field lines existed between the sunspot region and the filament in the sun's northern hemisphere.

This is an amazing event. A complex series of eruptions involving most of the visible surface of the sun has occurred, ejecting plasma toward the Earth. This coronal mass ejection (CME) rides the solar wind. Depending on the speed of the solar wind and the ejected plasma, this cloud will reach Earth's magnetosphere sometime between August 3 and August 5. High-latitude sky watchers should be alert for auroras. Radio communications by way of the ionosphere may become degraded soon after the CME arrives, and the degraded conditions may last for up to three days.

First view at the 304-Angstrom wavelength by SDO/AIA:
http://www.youtube.com/watch?v=VyaqxKkSCpU

Second view at the 171-Angstrom wavelength by SDO/AIA:
http://www.youtube.com/watch?v=HW_-yQY6YlA

Source: SDO/AIA

73 de NW7US, Tomas David Hood ( http://tomas-david-hood.com/ )

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Wednesday, October 01, 2008

Spotless Sun: Blankest Year of the Space Age

Astronomers who count sunspots have announced that 2008 is now the "blankest year" of the Space Age.

As of Sept. 27, 2008, the sun had been blank, i.e., had no visible sunspots, on 200 days of the year. To find a year with more blank suns, you have to go back to 1954, three years before the launch of Sputnik, when the sun was blank 241 times.

FULL STORY at
http://science.nasa.gov/headlines/y2008/30sep_blankyear.htm?list1066509

This is what a spotless sun looks like.

Friday, July 11, 2008

What's Wrong with the Sun? (Nothing)

Stop the presses! The sun is behaving normally.
By Dr. Tony Phillips: Science@NASA

So says NASA solar physicist David Hathaway. "There have been some reports lately that Solar Minimum is lasting longer than it should. That's not true. The ongoing lull in sunspot number is well within historic norms for the solar cycle."

This report, that there's nothing to report, is newsworthy because of a growing buzz in lay and academic circles that something is wrong with the sun. Sun Goes Longer Than Normal Without Producing Sunspots declared one recent press release. A careful look at the data, however, suggests otherwise.

But first, a status report: "The sun is now near the low point of its 11-year activity cycle," says Hathaway. "We call this 'Solar Minimum.' It is the period of quiet that separates one Solar Max from another."



The solar cycle, 1995-2015. The "noisy" curve traces measured sunspot numbers; the smoothed curves are predictions. Credit: D. Hathaway/NASA/MSFC

During Solar Max, huge sunspots and intense solar flares are a daily occurance. Auroras appear in Florida. Radiation storms knock out satellites. Radio blackouts frustrate hams. The last such episode took place in the years around 2000-2001.

During Solar Minimum, the opposite occurs. Solar flares are almost non-existant while whole weeks go by without a single, tiny sunspot to break the monotony of the blank sun. This is what we are experiencing now.

Although minima are a normal aspect of the solar cycle, some observers are questioning the length of the ongoing minimum, now slogging through its 3rd year.

"It does seem like it's taking a long time," allows Hathaway, "but I think we're just forgetting how long a solar minimum can last." In the early 20th century there were periods of quiet lasting almost twice as long as the current spell. (See the end notes for an example.) Most researchers weren't even born then.

Hathaway has studied international sunspot counts stretching all the way back to 1749 and he offers these statistics: "The average period of a solar cycle is 131 months with a standard deviation of 14 months. Decaying solar cycle 23 (the one we are experiencing now) has so far lasted 142 months--well within the first standard deviation and thus not at all abnormal. The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values."

In summary, "the current minimum is not abnormally low or long."

The longest minimum on record, the Maunder Minimum of 1645-1715, lasted an incredible 70 years. Sunspots were rarely observed and the solar cycle seemed to have broken down completely. The period of quiet coincided with the Little Ice Age, a series of extraordinarily bitter winters in Earth's northern hemisphere. Many researchers are convinced that low solar activity, acting in concert with increased volcanism and possible changes in ocean current patterns, played a role in that 17th century cooling.



For reasons no one understands, the sunspot cycle revived itself in the early 18th century and has carried on since with the familiar 11-year period. Because solar physicists do not understand what triggered the Maunder Minimum or exactly how it influenced Earth's climate, they are always on the look-out for signs that it might be happening again.

The quiet of 2008 is not the second coming of the Maunder Minimum, believes Hathaway. "We have already observed a few sunspots from the next solar cycle," he says. (See Solar Cycle 24 Begins.) "This suggests the solar cycle is progressing normally."

What's next? Hathaway anticipates more spotless days, maybe even hundreds, followed by a return to Solar Max conditions in the years around 2012.

Additional information and graphics on spotless days and this story is available at
http://science.nasa.gov/headlines/y2008/11jul_solarcycleupdate.htm?list1066509