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Title: Solar Wind Loses Power, Hits 50-year Low
Source:
NASA
URL Source: http://science.nasa.gov/headlines/y2008/23sep_solarwind.htm
Published: Sep 24, 2008
Author: not attributed
Post Date: 2008-09-24 10:33:28 by farmfriend
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Views: 116
Comments: 8
Sept. 23, 2008: In a briefing today at NASA headquarters, solar physicists announced that the solar wind is losing power. "The average pressure of the solar wind has dropped more than 20% since the mid-1990s," says Dave McComas of the Southwest Research Institute in San Antonio, Texas. "This is the weakest it's been since we began monitoring solar wind almost 50 years ago." McComas is principal investigator for the SWOOPS solar wind sensor onboard the Ulysses spacecraft, which measured the decrease. Ulysses, launched in 1990, circles the sun in a unique orbit that carries it over both the sun's poles and equator, giving Ulysses a global view of solar wind activity: Curiously, the speed of the million mph solar wind hasn't decreased much—only 3%. The change in pressure comes mainly from reductions in temperature and density. The solar wind is 13% cooler and 20% less dense. "What we're seeing is a long term trend, a steady decrease in pressure that began sometime in the mid-1990s," explains Arik Posner, NASA's Ulysses Program Scientist in Washington DC. How unusual is this event? "It's hard to say. We've only been monitoring solar wind since the early years of the Space Age—from the early 60s to the present," says Posner. "Over that period of time, it's unique. How the event stands out over centuries or millennia, however, is anybody's guess. We don't have data going back that far." Flagging solar wind has repercussions across the entire solar system—beginning with the heliosphere. The heliosphere is a bubble of magnetism springing from the sun and inflated to colossal proportions by the solar wind. Every planet from Mercury to Pluto and beyond is inside it. The heliosphere is our solar system's first line of defense against galactic cosmic rays. High-energy particles from black holes and supernovas try to enter the solar system, but most are deflected by the heliosphere's magnetic fields. "The solar wind isn't inflating the heliosphere as much as it used to," says McComas. "That means less shielding against cosmic rays." In addition to weakened solar wind, "Ulysses also finds that the sun's underlying magnetic field has weakened by more than 30% since the mid-1990s," says Posner. "This reduces natural shielding even more." Unpublished Ulysses cosmic ray data show that, indeed, high energy (GeV) electrons, a minor but telltale component of cosmic rays around Earth, have jumped in number by about 20%. These extra particles pose no threat to people on Earth's surface. Our thick atmosphere and planetary magnetic field provide additional layers of protection that keep us safe. But any extra cosmic rays can have consequences. If the trend continues, astronauts on the Moon or en route to Mars would get a higher dose of space radiation. Robotic space probes and satellites in high Earth orbit face an increased risk of instrument malfunctions and reboots due to cosmic ray strikes. Also, there are controversial studies linking cosmic ray fluxes to cloudiness and climate change on Earth. That link may be tested in the years ahead. Some of most dramatic effects of the phenomenon may be felt by NASA's two Voyager spacecraft. After traveling outward for 30+ years, the two probes are now at the edge of the heliosphere. With the heliosphere shrinking, the Voyagers may soon find themselves on the outside looking in, thrust into interstellar space long before anyone expected. No spacecraft has ever been outside the heliosphere before and no one knows what the Voyagers may find there. NASA is about to launch a new spacecraft named IBEX (short for Interstellar Boundary Explorer) that can monitor the dimensions of the heliosphere without actually traveling to the edge of the solar system. IBEX may actually be able to "see" the heliosphere shrinking and anticipate the Voyager's exit. Moreover, IBEX will reveal how our solar system's cosmic ray shield reacts to changes in solar wind. "The potential for discovery," says McComas, "is breathtaking."
Solar Wind Loses Power, Hits 50-year Low
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#1. To: All (#0)
Interesting that this comes as there are no sun spots. The strength of solar wind has been shown to effect cloud cover as well.
The first sunspot happened in the last few days, dipshit.
Sunspot 1002 is now a plage region and appears that no sunspots are visible. In a matter of 3 days it went from a new Cycle 24 plage to mini sunspot cluster and back to a plage again. If sunspot activity for the month of September 2008 remains the way it is now until the end of the month, It will mark the first month where Cycle 24 activity outnumbers Cycle 23 activity (As small as it may be). From the Space Weather Prediction Center Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 267 Issued at 2200Z on 23 Sep 2008 Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity was very low. No flares occurred during the past 24 hours. Region 1002 (N26W40) was quiet and stable and has decayed to a small C-type sunspot group. Solar Activity Forecast: Solar activity is expected to be very low. Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic field was quiet during the past 24 hours. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet for the next three days (24-26 September).
#6. To: farmfriend (#5)
I know you are a women, and not being too bright, let me "enlighten" you. http://www.universetoday.com/2008/09/22/solar-cycle-24-sunspots-finally-say-hello/ After an extended period of calm for Solar Cycle 24, a cluster of sunspots have appeared on the disk of the Sun. Although we have observed sunspots since the beginning of this new solar cycle (which officially began on January 4th, 2008 with the observation of a high-latitude sunspot pair), this is the first time for many months "new" Cycle 24 sunspots have shown themselves. Before today, the sunspots (including occasional flares and coronal mass ejections) belonged to the previous cycle (Cycle 23). It would appear the spots have evolved into a cluster in a high-latitude location with the magnetic polarity consistent with this new cycle. But does this mean we can expect an increase in solar activity after this pretty dull period of "blank" solar disk observations? Your guess is as good as mine… Overlapping solar cycles are natural occurrences, and extended solar minima are not unexpected, but many predictions of an extended period of solar calm have been put forward since Solar Cycle 24 appeared to shy away after the initial excitement in January. Although the Sun has been surprisingly quiet for several months, we've still had sporadic sunspot activity (plus the occasional flare and CME eruption), but none could be attributed to the new Cycle 24 (although I erroneously thought the August sunspot activity was due to Cycle 24, it was in fact due to the overlapping Cycle 23). A closeup of the Cycle 24 spots. Observed on September 22nd at Selsey, West Sussex, UK (© Pete Lawrence) A closeup of the Cycle 24 spots. Observed on September 22nd at Selsey, West Sussex, UK (© Pete Lawrence) So how can we be so sure these new observations are of Cycle 24 spots and not Cycle 23 spots? After quickly glancing at the Solar and Heliospheric Observatory (SOHO) image (top), we can see a cluster of activity at a fairly high latitude. Generally speaking, one would expect sunspots at the beginning of a new cycle to appear at high latitudes. As the 11-year solar cycle progresses, sunspot activity will begin to drift equator-wards, to lower latitudes. "Old" Cycle 23 sunspots have generally appeared near the solar equator, so the sunspots observed today can be attributed to the "new" Cycle 24. The clincher for identifying these spots as belonging to a new solar cycle is their magnetic polarity. Sunspots often appear in pairs of opposite polarity (i.e. one will be magnetic north, the other will be magnetic south), and this new cluster is consistent with the polarity expected for Cycle 24 sunspots. SOHO uses its Michelson Doppler Imager (MDI) Magnetogram instrument to observe magnetic polarity, and it would appear that the polarity of this sunspot cluster has an opposite magnetic north/south to previous Cycle 23 observations. So does this mean we might see an increase in solar activity from here on in? Although this is an encouraging observation, the Sun could revert back to its "blank" state as quickly as it revealed these sunspots to SOHO. However, there is also a chance this could herald the beginning of accelerated solar activity, possibly still fulfilling NASA's 2006 prediction that Solar Cycle 24 will be a "doozy." Watch this space… Original source: Space Weather Filed under: Solar Astronomy
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#4. To: farmfriend (#1)
Interesting that this comes as there are no sun spots. The strength of solar wind has been shown to effect cloud cover as well.
#5. To: Ninpo (#4)
The first sunspot happened in the last few days, dipshit.
Su ns pot 1002 now a Plage
09/24/2008 by Kevin VE3EN at 13:20 
Updated 2008 Sep 23 2201 UTC
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