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Category Archives: 10. Our star: the Sun

Earlier this year, NASA’s Interface Region Imaging Spectrograph (IRIS) spacecraft captured its first observations of a region of the Sun that is now possible to observe in detail: the lowest layers of the Sun’s atmosphere, the solar interface region.

Credit: NASA Goddard

The first images from IRIS show the solar interface region in unprecedented detail. They reveal dynamic magnetic structures and flows of material in the Sun’s atmosphere and hint at tremendous amounts of energy transfer through this little-understood region. These features may help power the Sun’s dynamic million-degree atmosphere and drive the solar wind that streams out to fill the entire Solar System.

The energy flowing through the interface region powers the upper layer of the Sun’s atmosphere, the corona, to temperatures greater than 1.8 million degrees Fahrenheit (1 million K). That is almost a thousand times hotter than the Sun’s surface. Understanding the interface region is important because it drives the solar wind and forms the ultraviolet emission that impacts near-Earth space and Earth’s climate.

IRIS is a NASA Small Explorer mission that was launched on June 27, 2013. Its instrument is a combination of an ultraviolet telescope and a spectrograph.

Links: NASA press release and IRIS mission homepage.

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p. 277: A Closer Look 10.2. Solar Eclipses of 2013

The two eclipses shown, both from Australia, are actually November 14, 2012, for the total solar eclipse and May 10, 2013, for the annular eclipse.