Sun-Earth Connections part of a symposium at the Tacoma campus of The Evergreen State College 14.Sept.2001 The Sun and the Earth are both getting hotter. What does the Sun’s magnetic activity have to do with it? What are the consequences? We are investigating questions like these in classes and research at Evergreen. Dr. E.J. Zita, The Evergreen State College, Olympia, WA

Outline: Sun radiates Earth Earth and Sun are warming Magnetic activity heats the Sun’s atmosphere Solar magnetism affects the Earth How do we measure effects on Earth? On Sun? How do magnetic fields affect the Sun? How can we predict magnetic storms? What can we do about it? Evergreen contributes to understanding the Sun

Sun radiates Earth Nuclear fusion  energetic photons  light and heat Hot gas  energetic charged particles  solar wind Diagrams courtesy of NCAR

Sun and Earth are warming From Friis-Christensen, E., and K. Lassen, "Length of the solar cycle: An indicator of solar activity closely associated with climate," Science, 254, , See The Sun gets bigger and hotter as it grows older (billions of years). The Earth is currently warming out of latest ice age (13,000 yrs). Many factors contribute to (long-term) climate changes and (short-term) temperature variations on Earth. Earth’s average temperature (blue) tracks solar activity (red).

Magnetic activity heats the Sun’s atmosphere Diagrams courtesy of Campfire: hot inside, cooler as you move away Sun: Hot inside, cool surface, but hotter as you move away!

Solar magnetism affects the Earth Movies courtesy of Magnetic field lines snap  release hot ions aurorae: solar ions trapped in Earth’s magnetic field magnetic storms  power and satellite outages

How do we measure effects on Earth? Diagram courtesy of NCAR Solar observatories: Measure luminosity, count sunspots Weather stations: Earth temperatures, atmospheric effects

How do we measure effects on the Sun? TRACE: measures fine-scale solar magnetic fields SOHO: Solar and Heliospheric Observatory: coronal spectra YOHKOH: (Japanese for sunbeam) measures high-energy radiation from solar flares (X-rays and neutrons) and quiet structures and pre-flare conditions.

How do magnetic fields affect the Sun? Diagram courtesy of Gregory, Stephen A., and Michael Zeilik. Introductory Astronomy and Astrophysics. Magnetic field lines rise from inside sun  sunspots Twisted field lines  increased magnetic energy Magnetic reconnection  release particles and kinetic energy Magnetic waves  heating Figure 4 Gregory, p.220

Magnetic waves in Sun’s atmosphere Created with 3D MHD code by Rosenthal et al., Oslo Research by Evergreen students at NCAR, Boulder Sara Petty-Powell and Matt Johnson

How can we predict magnetic storms? Diagrams courtesy of Montana State University and NCAR Twisting magnetic fields  s-shaped filaments on photosphere  field lines snap and reconnect  energy release Dooling, p. 2 (Dooling, Dave. p. 2) Figure 9

Waves in twisted magnetic fields Diagrams courtesy of Montana State University Research by Evergreen faculty at NCAR, Boulder E.J. Zita with Tom Bogdan and B.C. Low

What can we do about it? Not a darn thing? the Sun does what it will prevention: redesign power circuits and satellites understand the Sun better: predict magnetic storms and protect satellites enjoy the increased warmth and aurorae

Evergreen contributes understanding Theory: Zita calculates magnetic waves in Sun’s atmosphere Modeling: colleagues in Oslo solve equations with computers to generate numerical data (Rosenthal et al.) Observations: colleagues at NCAR and elsewhere observe Sun with satellites to get real data (Lites et al.) Analysis: Students help us understand how numerical data connects to theory and real data (Bogdan et al.) theory modeling Observations analysis

Summary Diagram courtesy of HAO and WET Solar magnetic activity  greater energy from Sun  greater temperatures, aurorae, magnetic storms on Earth Multifacted collaboration  better understanding of Sun and Earth

Selected references GONG & NOAO = Global Oscillation Network Group NCAR = National Center for Atmospheric Research, Boulder, CO MSU = Montana State University Stanford Solar Center SOHO: Kaler, James B. Stars. New York: Scientific American Library, NASA: Institute for Physics and Astronomy, Aarhus University, Denmark Waves in the magnetic solar atmosphere I, Colin Rosenthal and Tom Bogdan, Astrophysical Journal, 2001 Energy transport by waves above the photosphere, Sara Petty-Powell and Matt Johnson, 2001 Wave transformations in a sheared, force-free magnetic field, E.J. Zita,