Scientists Successfuly Predict the Shape of the Corona Seen at the Solar Eclipse

Media contact: Jay Pasachoff, [email protected]

Scientists Successfully Predict the Shape of the Corona Seen at the Solar Eclipse

WILLIAMSTOWN, Mass., August 27, 2018—Last summer’s solar corona was spectacular at the August 21 total solar eclipse, but a team of scientists had predicted its shape pretty well.  This pearly white halo of brightness around the sun, normally hidden behind the blue sky, is actually spiky, like a porcupine’s quills.  During the eclipse, for those in the 60-mile-wide band of totality that stretched from Oregon through parts of 14 states to South Carolina, viewers were treated to streamers to the sides of the sun, starting broad at their bases and coming to points at higher levels, while thin plumes of gas were visible at the sun’s north and south poles.

The overall form of the streamers was predicted on the basis of the sunspots and magnetic field on the everyday sun’s surface over the preceding month, as described in a scientific paper appearing today (August 27) in the journal Nature Astronomy.  Led by its scientists Zoran Mikic, Cooper Downs, and Jon Linker of Predictive Science, a research company based in San Diego, California, a few days before the eclipse the team posted a prediction of the shape of the corona.

The published Nature Astronomy paper compared the calculated advance appearance of the corona with actual coronal images.  However, because the corona falls off in brightness by 1000 times within the first sun’s radius above its edge, dozens of individual photographs must be combined to show the shapes of the corona over a wide range of heights.  In the article, high-contrast images composited by Czech computer scientist Miloslav Druckmüller from the Brno University of Technology and lower-contrast images in a collaboration between Williams College astronomer Jay Pasachoff with computer work by New York electronic-music expert Wendy Carlos both showed successful agreement with the predictions.

Other scientists involved in the published paper are Ronald M. Caplan, Duncan Mackay, Lisa Upton, Pete Riley, Roberto Lionello, Tibor Török, Viacheslav Titov, Janvier Wijaya of Predictive Science; Lisa Upton of the High Altitude Observatory of Boulder, Colorado; and Duncan Mackay of the University of St. Andrews, Scotland.  Upton’s and Pasachoff’s work was sponsored by the Atmospheric and Geospace Sciences Division of the U.S. National Science Foundation.  Pasachoff had additional support from the Committee for Research and Exploration of the National Science Foundation, and is a Visitor at the Carnegie Observatories in Pasadena, California.

Acknowledgments: This research was supported by NASA (Heliophysics Supporting Research and Living with a Star programs), U.S. Air Force Office of Scientific Research, and the National Science Foundation (NSF).  Mikic acknowledges support from NASA grants NNX16AH03G and NNX15AB65G. Computations were provided by NASA’s Advanced Supercomputing Division, NSF’s Texas Advanced Computing Center, and San Diego Supercomputer Center. Data courtesy of NASA/SDO and the AIA and HMI science teams. The authors acknowledge the International Space Science Institute in Bern, Switzerland, for hosting a team on “Global Non-Potential Magnetic Models of the Solar Corona,” led by A. Yeates, where some of the ideas were developed. The Solar Physics Group at Stanford University provided timely access to magnetic-field data from their Helioseismic Magnetic Imager aboard NASA’s Solar Dynamics Observatory. Additional data was provided by the Mauna Loa Solar Observatory, operated by the High Altitude Observatory, as part of the National Center for Atmospheric Research (NCAR).

The Williams College Eclipse Expedition was supported in large part by grants from the Solar Terrestrial Program of the Division of Atmospheric and Geospace Sciences of the NSF (Award AGS-1602461) and from the Committee for Research and Exploration of the National Geographic Society (Grant 9878-16), with additional support from the NASA Massachusetts Space Grant Consortium, the Sigma Xi scientific research honor society and the Clare Booth Luce Foundation.  Lisa Upton was supported by the NSF Atmospheric and Geospace Sciences Postdoctoral Research Fellowship Program (Award AGS-1624438) and is hosted by the High Altitude Observatory at the National Center for Atmospheric Research.

reference: Zoran Mikic, Cooper Downs, Jon A. Linker, Ronald M. Caplan, Duncan Mackay, Lisa Upton, Pete Riley, Roberto Lionello, Tibor Török, Viacheslav Titov, Janvier Wijaya, Miloslav Druckmüller, Jay M. Pasachoff, and Wendy Carlos, 2018, “Predicting the Corona for the 21 August 2017 Total Solar Eclipse,” Nature Astronomy.

DOI for this paper will be 10.1038/s41550-018-0562-5. Once the paper is published electronically, the DOI can be used to retrieve the abstract and full text by adding it to the following url: http://dx.doi.org/

contact information:

Zoran Mikic, [email protected]

Jay Pasachoff, [email protected]

August 11, 2018, partial solar eclipse observations: https://communications.williams.edu/news-releases/swedeneclipse/

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