space probes. Despite all that has been learned by the [*in situ*]{} detection of particles and fields, though, we have learned the most about how the solar wind is produced from good, old-fashioned astronomical imaging and spectroscopy. This paper summarizes the most recent results of this kind from the past decade of observations with the [*SOHO*]{} spacecraft. (A top-ten list of reasons “Why stellar astronomers should be interested in the Sun” is given in an article with that title by Schmelz 2003).

Brief History (pre-SOHO)
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Sightings of the solar corona and the shimmering aurora (i.e., the beginning and end points of the solar wind that encounters the Earth) go back into antiquity. The first scientific understanding of the outer solar atmosphere came as spectroscopy began to be applied to heavenly light in the late 19th century. In 1869, Harkness and Young first observed the 5303 [å]{} coronal green line during a total eclipse. Soon after, in the very first issue of [*Nature,*]{} J.  Norman Lockyer (the discoverer of helium) reported that these observations were “...[*[bizarre]{}*]{} and puzzling to the last degree!” The chemical element responsible for the green line went unidentified for 70 years, after which Grotrian and Edlén applied new advances in atomic physics to show that several of the coronal emission lines are produced by very high ionization stages of iron, calcium, and nickel. The puzzle then shifted to explaining what causes the outer solar atmosphere to be heated to temperatures of more than 10$^6$ K. Despite many proposed theoretical processes, this “coronal heating problem” is still with us today because there are no clear observational constraints that can determine which if any of the competing mechanisms is dominant.

Knowledge about an outflow of particles from the Sun was starting to coalesce at the beginning of the 20th century. Researchers came to notice strong correlations between sunspot activity, geomagnetic storms, auroral appearances, and 