I initially wrote this article using data only from David Archibald, but within a couple of minutes I was given some broader data from Leif Svalgaard, so I have rewritten this to include both resources in the interest of seeing the broader perspective. – Anthony
Last September WUWT covered NASA’s press conference on the state of the sun. One of the announcements was this:
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.”
From Wiki:
The solar wind is a stream of charged particles—a plasma—ejected from the upper atmosphere of the sun. It consists mostly of electrons and protons with energies of about 1 keV. The stream of particles varies in temperature and speed with the passage of time. These particles are able to escape the sun’s gravity, in part because of the high temperature of the corona, but also because of high kinetic energy that particles gain through a process that is not well-understood.
The solar wind creates the Heliosphere, a vast bubble in the interstellar medium surrounding the solar system. Other phenomena include geomagnetic storms that can knock out power grids on Earth, the aurorae such as the Northern Lights, and the plasma tails of comets that always point away from the sun.
The solar wind is a stream of charged particles—a plasma—ejected from the upper atmosphere of the sun. It consists mostly of electrons and protons with energies of about 1 keV. The stream of particles varies in temperature and speed with the passage of time. These particles are able to escape the sun’s gravity, in part because of the high temperature of the corona, but also because of high kinetic energy that particles gain through a process that is not well-understood.
The solar wind creates the Heliosphere, a vast bubble in the interstellar medium surrounding the solar system. Other phenomena include geomagnetic storms that can knock out power grids on Earth, the aurorae such as the Northern Lights, and the plasma tails of comets that always point away from the sun.
Solar Wind Flow Pressure is something that is tracked daily by the Space Weather Prediction Center (SWPC) For example they display a nifty solar wind dashboard gauge on Space Weather Now that shows “dynamic pressure”:
Click dial for an explanation of the readings
Dynamic Pressure Dial:
Ranges from 0.1 to 100 nPa. The scale is log10 over the full range. If the density or speed data are missing, the arrow will not appear. The arrow will move to the location on the scale corresponding to the actual value of the latest 15 minute average of the Dynamic Pressure P of the solar wind. Dynamic Pressure is a function of speed and density.
David Archibald writes: Read the rest of this entry »
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