Solar magnetic field
Sheeley, Neil R., Jr. Naval Research Laboratory, Washington, DC.
Last reviewed:January 2020
- Bipolar regions and sunspots
- Unipolar regions and polar fields
- Mixed-polarity regions
- Outward extension of the field
- Solar variability and other stars
- Origin of bipolar fields
- Related Primary Literature
- Additional Reading
The magnetic field rooted in the Sun and extending out past the planets into the solar system. The field at the Sun's surface is detected remotely by its effect (the Zeeman effect) on atoms whose radiation is observed from Earth. This technique was first applied at the Mount Wilson Observatory in 1908 by G. E. Hale to detect the fields in sunspots. In 1952, H. D. Babcock and his son H. W. Babcock used a scanning technique to make the first magnetic maps of the entire visible disk of the Sun. Their daily “magnetograms” soon revealed a variety of magnetic features, including bipolar regions associated with sunspot groups, and unipolar regions whose fields extend far from the Sun and are responsible for recurrent geomagnetic activity at Earth. The field strengths range from a few gauss (a few hundred microtesla) in quiet areas to 3500 gauss (0.35 tesla) in sunspots. In 1962, the Mariner 2 spacecraft, en route to Venus, made the first on-site sampling of the extended solar field in space. The average field strength was only 50 microgauss (5 nanotesla), reflecting the rapid (inverse square) fall-off of field strength with distance from the Sun. See also: Zeeman effect
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information