Corona shape during the total eclipse on August 21, 2017

I took a single picture during totality with my old smartphone, but at least I put it in high dynamic range mode (HDR). (C) 2017 Tobias Kramer
Eclipse path on August 21, 2017 near Salem, Oregon, USA. I was positioned at the red marker. I computed the path with my venerable eclipse prediction program from 1994 following the algorithms given in the Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac (1961 edition) p. 211ff.

I was lucky to witness the total eclipse under perfect weather conditions in Salem, Oregon. Salem was very accessible with public transport (Amtrak trains arriving before the eclipse, special stop to accommodate people getting off to viewing locations). While this picture does little justice to the real impression of the “inverted Sun” (dark disk with bright corona around it), it shows the irregular “triangular” shape of the corona with three rays  poking out. From Earth it is normally impossible to see the corona due to scattered light in the atmosphere, but solar satellites monitor the Sun constantly. I followed NASA’s example and overlaid a space satellite image with my image (after rotating it such that  the ecliptic plane [conveniently  indicated by Venus] aligns horizontally). If you want to try something similar yourself, I recommend the helioviewer website for easy selection and download of the solar satellite imagery. To match the scales on your pictures: Venus is 34.3 degrees away from the Sun, corresponding to about 130 solar radii. We are presently close to a minimum of solar activity and thus the corona less roundish.

Overlay of the solar eclipse image taken by Tobias Kramer at Salem with the SOHO LASCO C3 image 2017-08-21 16:54:07 UTC. The 3 rays visible by SOHO are causing the triangular shape of the corona as seen during the eclipse.

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