Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 September 27
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Layers of a Total Solar Eclipse
Image Credit: Inside: Solar Dynamics Observatory, LMSAL and NASA’s GSFC;
Middle: Jay Pasachoff, Ron Dantowitz, and the Williams College Solar Eclipse Expedition/NSF/National Geographic;
Outside: LASCO from NRL on SOHO from ESA

Explanation: Neither rain, nor snow, nor dark of night can keep a space-based spacecraft from watching the Sun. In fact, from its vantage point 1.5 million kilometers sunward of planet Earth, NASA's SOlar Heliospheric Observatory (SOHO) can always monitor the Sun's outer atmosphere, or corona. But only during a total solar eclipse can Earth-based observers also see the lovely coronal streamers and structures - when the Moon briefly blocks the overwhelmingly bright solar surface. Then, it becomes possible to follow detailed coronal activity all the way down to the Sun's surface. In the outside layer of this composite image, SOHO's uninterrupted view of the solar corona during last month's eclipse is shown in orange hues. The middle, donut-shaped region is the corona as recorded by the Williams College Eclipse Expedition to Salem, Oregon. Simultaneously, the inner view is from NASA's Earth-orbiting Solar Dynamics Observatory, which, being outside of totality, was able to image the face of the Sun in extreme ultraviolet light, shown in gold.

Tomorrow's picture: open spacetime

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