Partial Solar Eclipse, Oct 23, 2014

                     Fiske/SBO Special Observing Event


annular eclipse path Sommers-Bausch Observatory will be holding a special celestial event for students on Thursday October 23rd, 2014, to view the partial solar eclipse. Fiske Planetarium will be holding an event for the public.

About 25% of the Sun will be obscured by the Moon. 

SunMoon Image

While most people think that solar eclipses (total and/or annular) are much rarer than total lunar eclipses, in fact the solar eclipse is (slightly) more common: about one solar eclipse occurs (somewhere) every 1.5 years. The reason that solar eclipses seem to be rare is because one has to be in exactly the right place at the right time to see it, standing along the tiny umbral shadow (corresponding to the red dot in the animation). On the other hand, all that is required to see a total lunar eclipse is for the observer to be standing anywhere in the nighttime hemisphere of the Earth when it happens! Thus, it turns out, that there is only about one chance in 360 that you'll see a total solar eclipse path cross your doorstep in a single year; but there is one chance in 3 that a lunar eclipse will occur during your nighttime in a given year!

In case you'd like to see a true total eclipse of the Sun, all you have to do is wait until August 21st, 2017 - and also travel into Wyoming, about 60 miles north of Cheyenne! If you're content to stay in Boulder, well, you'll see 97% if the Sun disappear; it will become quite dark at noontime, and shadows will look quite crisp and bizarre - but you'll entirely miss seeing the solar chromosphere and corona.

Here is the timetable of aspects of the eclipse this time around (October 14th), as seen from Boulder; all times are local Mountain Daylight Time.

Phase LT AZ Alt Ha Airmass
First contact 3:22:14 pm 223d 57' 33"
26d 52' 12"
+02h 36m 49s
Greatest 4:24:08 pm 237d 02' 14"
17d 42' 16"
+03h 38m 45s
Final contact
5:45:14 pm 251d 25' 26"
3d 43' 02"
+04h 59m 51s

Viewing the Eclipse

The easiest way to see the eclipse is to watch it from where you're sitting right now, by clicking this SBO Streaming Video link. Weather permitting, we'll be web-casting the Sun in Hydrogen-alpha throughout the eclipse with our heliostat (solar telescope) at Sommers-Bausch Observatory and streaming it to you via a Ustream channel. We'll be using a Halle hydrogen-alpha filter to permit only the light emitted by hydrogen atoms in the solar atmosphere (at a wavelength of 6563 Angstroms, or 656.3 nanometers) to form the images. This technique permits us to see the solar chromosphere, or "sphere of color", that overlies the white-light view of the photosphere (where sunspots are apparent). The chromosphere is much richer in detail than the photosphere, with its prominences, filaments, plagues, and an occasional flare.

Finally, of course, we'll have mylar sunglasses available on sale at Fiske, which you can use either here at SBO,  or at the Eclipse Extravaganza over at Folsom Stadium. You can also re-use them in a couple of weeks for the Venus transit of the Sun on June 5th - as well as for those upcoming 2014 and 2017 eclipses!

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