Solar physicists¹ attempting to unlock the mysteries of the solar corona日冕 have found another piece of the puzzle by observing the sun's outer atmosphere during eclipses. Ground-based observations reveal the first images of the solar corona² in the near-infrared emission³ line of highly ionized电离 iron, or Fe XI 789.2 nm. The observations were taken during total solar eclipses in 2006, 2008, and 2009 by astrophysicist Adrian Daw of NASA's Goddard Space Flight Center in Greenbelt, Md., with an international team of scientists led by Shadia Habbal from the University of Hawaii's Institute for Astronomy (IfA).

"The first image of the corona in Fe XI 789.2 nm was taken during the total solar eclipse of March 29, 2006," said Daw.

The images revealed some surprises. Most notably⁴, that the emission extends out at least three solar radii半径—that's one-and-a-half times the sun's width at its equator赤道, or middle—above the surface of the sun, and that there are localized regions of enhanced density⁵ for these iron ions.

Combined with observations of other iron charge states, the observations yield the two-dimensional distribution of electron temperature and charge-state measurements for the first time, and establish the first direct link between the distribution分配，分布 of charge states in the corona and in interplanetary space行星际空间. "These are the first such maps of the 2-D distribution of coronal electron temperature and ion离子 charge state," said Daw.

Mapping the distribution of electron temperature and iron charge states in the corona with total solar eclipse observations represents an important step in understanding the solar corona and how space weather impacts Earth.