starship-design: Fwd: Ulysses Forecasts Weather at Sun's North Pole

[Curtis Manges <clmanges@yahoo.com>]

Just another FYI that caught my attention. Enjoy.

Curtis


--- JPLNews@jpl.nasa.gov wrote:
> Date: Fri, 31 Aug 2001 16:19:06 -0700 (PDT)
> From: JPLNews@jpl.nasa.gov
> Subject: Ulysses Forecasts Weather at Sun's North Pole
> Reply-to: news-owner@www.jpl.nasa.gov
> To: undisclosed-recipients:;
> 
> MEDIA RELATIONS OFFICE
> JET PROPULSION LABORATORY
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> Contact: Martha J. Heil      (818) 354-0850                  
> 
> FOR IMMEDIATE RELEASE                         Aug. 31, 2001
> 
> ULYSSES FORECASTS WEATHER AT SUN'S NORTH POLE
> 
>      Space physicists predict gusty winds for the next few 
> months at the Sun's north pole, an area that will be observed 
> when the Ulysses spacecraft passes over it starting on Aug. 
> 31.
> 
>      This pass over the pole occurs at a time of solar 
> maximum, when the Sun is more active. "The solar wind is 
> patchier -- gustier -- during solar maximum, because the 
> sources of the wind are more irregular," said Dr. Edward 
> Smith, the project scientist at NASA's Jet Propulsion 
> Laboratory on Ulysses, which is managed jointly by JPL and the 
> European Space Agency.
> 
>      This will be Ulysses' second pass over the Sun's north 
> pole. It completed a circuit of the Sun in 1996 when the Sun 
> was less active, then passed by the Sun's south pole last fall 
> when the Sun was much more active. Now scientists will use 
> what they've learned from previous passes to analyze data in 
> the coming months.
> 
>      Earth's magnetic field reverses itself only once every 
> 200,000 years or so, but the Sun's internal magnet flips every 
> 11 years, associated with a rise in solar activity. As it 
> flips, the magnetic field becomes disordered, and the surface 
> of the Sun becomes more active, shooting out bubbles of gas 
> and energy called coronal mass ejections in every direction. 
> The reversal of the magnetic field has a particularly dramatic 
> effect on the poles. The Sun's magnetic field will be weak and 
> X-ray coronal holes at the north pole should have shrunk 
> during this solar maximum, because the magnetic field is 
> unevenly spread around the surface of the Sun.
> 
>      In 1995, Ulysses saw strong and simple magnetic fields at 
> both poles of the Sun.  Large, dark X-ray coronal holes formed 
> in the solar atmosphere over the polar caps. The solar wind is 
> fast and hot when coronal holes in the Sun remain open over 
> long periods of time, as they do at solar minimum. 
> 
>      As Ulysses passed by the south pole of the Sun a few 
> months ago, scientists expected to find that magnetic lines 
> were pointing outward, because observations from Earth show 
> that the magnetic field has already reversed at the Sun's 
> surface. Instead, they found that the magnetic lines were 
> still pointing inward, just as they had been throughout solar 
> minimum. They theorize that this could be caused by the 
> magnetic lines forming small, closed loops next to the pole 
> instead of escaping into space. For now, the magnetic field 
> and solar wind seen over the pole appear to originate near the 
> Sun's equator rather than from the polar cap.
> 
>      The Ulysses science team will also study energetic 
> charged particles, which speed away from the Sun's surface and 
> escape into space. These are a regular feature of solar 
> maximum.  "These energetic solar particles can be as hot as 
> 100 billion Kelvin (180 billion Fahrenheit) and can cause 
> damage to spacecraft," said Dr. Bruce Goldstein, deputy 
> project scientist on Ulysses at JPL. "However, they still 
> follow the magnetic field lines." 
> 
>      At solar minimum, Ulysses saw very few particles coming 
> from the poles. This was because there were fewer particle 
> events occurring on the Sun and also because the particles 
> follow magnetic lines of force that did not reach into the 
> Sun's polar regions. 
> 
>      As it studied the south pole during solar maximum, 
> Ulysses saw energetic particles from many of the past year's 
> solar flares, though they originated at the Sun's equator. 
> Those observations are further evidence that the magnetic 
> field and solar wind seen at the polar caps really originate 
> close to the equator.
> 
>      Ulysses, launched in 1990, is a joint venture of NASA and 
> the European Space Agency. JPL manages Ulysses for NASA's 
> Office of Space Science, Washington, D.C. More information on 
> the Ulysses mission is available at the JPL Ulysses web site: 
> http://ulysses.jpl.nasa.gov and the ESA Ulysses web site, 
> http://helio.estec.esa.nl/ulysses/ .
> 
>                         # # # # #
> 09/03/01 MJH
> #2001-182
> 
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=====
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