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THE SUN  

Why We Study the Sun  
The Big Questions  
Magnetism - The Key  

SOLAR STRUCTURE  

The Interior  
The Photosphere  
The Chromosphere  
The Transition Region  
The Corona  
The Solar Wind  
The Heliosphere  

SOLAR FEATURES  

Photospheric Features  
Chromospheric Features  
Coronal Features  
Solar Wind Features  

THE SUN IN ACTION  

The Sunspot Cycle  
Solar Flares  
Post Flare Loops  
Coronal Mass Ejections  
Surface and Interior Flows
Helioseismology  

THE MSFC SOLAR GROUP  

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RESEARCH AREAS  

Flare Mechanisms  
3D Magnetic Fields  
The Solar Dynamo  
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Sunspot Database  
Coronal Heating  
Solar Wind Dynamics  

PREVIOUS PROJECTS  

Orbiting Solar Obs.  
Skylab  
Solar Maximum Mission  
SpaceLab 2  
MSSTA  
GOES SXI Instrument  
Yohkoh  

CURRENT PROJECTS  

MSFC Magnetograph  
The Hinode Mission  
The STEREO Mission  
The RHESSI Mission  
The Ulysses Mission  
The GONG Project  
The SOHO Mission  
The TRACE Mission  
The Sun in Time (EPO)  

FUTURE PROJECTS  

The SDO Mission  
Solar Probe  
Interstellar Probe  

Solar Wind Features

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Click on image for animation.

Magnetic Clouds

Magnetic Clouds are produced in the solar wind when solar eruptions (flares and coronal mass ejections) carry material off of the Sun along with embedded magnetic fields. These magnetic clouds can be detected in the solar wind through observations of the solar wind characteristics - wind speed, density, and magnetic field strength and direction.

Corotating Interactive Regions

Co-rotating Interactive Regions (CIRs) are regions within the solar wind where streams of material moving at different speeds collide and interact with each other. The speed of the solar wind varies from less than 300 km/s (about half a million miles per hour) to over 800 km/s depending upon the conditions in the corona where the solar wind has its source. Low speed winds come from the regions above helmet streamers while high speed winds come from coronal holes. As the Sun rotates these various streams rotate as well (co-rotation) and produce a pattern in the solar wind much like that of a rotating lawn sprinkler. However, if a slow moving stream is followed by a fast moving stream the faster moving material will catch-up to the slower material and plow into it. This interaction produces shock waves that can accelerate particles to very high speeds.

Composition Variations

The chemical composition of the solar wind has several interesting aspects that hint at physical processes that occur in the solar wind source regions. The solar wind composition is different from the composition of the solar surface and shows variations that are associated with solar activity and solar features.

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Web Links
NOAA's Space Environment Center - Current Space Weather Conditions Updated Every 5-minutes
SpaceWeather.com - Space Weather Homepage Updated Daily
SolarStorms.org - Learn More About Space Weather and Solar Storms
National Space Weather Program - The U.S. Government and Space Weather
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+ Visit Solar Terrestrial Probes Program
+ Visit Living With a Star Program
NASA Logo Image Author: Dr. David H. Hathaway, david.hathaway @ nasa.gov
Curator: Mitzi Adams, mitzi.adams @ nasa.gov

Last Updated: January 18, 2007