Approximately 150 students, faculty, staff and friends turned out to watch the solar eclipse from the courtyard in front of Frederick Reines Hall at UC Irvine. The eclipse lasted from approximately 5:16 pm to 7:23 pm, with the maximum occurring at 6:22 pm. We thank the Astronomy Club at UCI for hosting the event, and we thank all our visitors for their abundance of enthusiasm and insightful questions! Those of you interested in future solar and lunar eclipses can check out the "Eclipse Home Page" at NASA/Goddard Space Flight Center run by Fred Espenak .
 

Photo 1: The image of the Sun was projected onto a screen using a Celestron 6" telescope (see Photo 3 below) ,which had been stopped down in aperture in order not to heat and damage the optics of the telescope. The shadow of the telescope is visible on the screen, too. In this photo, the eclipse is just beginning.		Photo 2: A while later, the Moon has moved to eclipse an even greater fraction of the Sun. At maximum, approximately 72% of the Sun's area was occulted by the Moon. At locations further south, such as in Baha, Mexico, the eclipse was nearly total (97% of the Sun eclipsed).
Photo 3: Eclipse watchers view the progress of the Moon across the face of the Sun in the projected image, while others uses "solar eclipse shades" to view the Sun directly.		Photo 4: Eclipse watchers could also view the Sun using a second telescope equipped with a filter.
Photo 5: The crowd grows as the eclipse reaches maximum.

     Prior to the eclipse, four sunspots were clearly visible on the face of the Sun. The next day's photograph of the Sun made by the National Solar Observatory at Kitt Peak, which is shown below, shows them in more detail. (In the photo below, North is up and East to the left. To get the same orientation as the image we projected onto the screen - Photo 1 - one would rotate the image below by 90 degrees counter-clockwise and flip the x axis.) At its equator, the Sun rotates once around its axis every 25 days, although at the Sun's poles the rotation rate is longer, 36 days. Thus in the day since the eclipse the sunspots have moved roughly 10 degrees toward the left in the photo below.
     Sunspots are pockets of gas on the surface of the Sun that are a few thousand degrees cooler than the surrounding gas. They might have a typical temperature of 4000 degrees Kelvin whereas the average temperature is 6000 degrees Kelvin [1]. Sunspots are cool because a stronger than average magnetic field in them inhibits warmer gas underneath them from flowing to the surface. The gas in the sunspot will cool and radiate energy, growing dimmer, but warmer gas from beneath cannot rise and replace it. Normally, the surface of the sun contantly boils as convection causes pockets of warm gas to rise and cool gas to fall inward. Sunspots generally grow in size over the timescale of a few days, and then slowly fade away, lasting for a maximum of a few weeks.

Notes:
[1] The conversion from temperature in degrees Kelvin, T_k, to temperature in degrees Fahrenheit, T_f, is:
     T_f = -459 + 1.8*T_k
[2] Photos courtesy of T. Smecker-Hane, L. Chang, and the National Solar Observatory.