One more IYA event - today is Sun Day!

[Jane Houston Jones]

It's IYA Sun Day!

Join me this afternoon from 1:30 until 3 p.m. Myrtle and Lime Streets 
Monrovia CA for the Old Town Sidewalk Astronomers fourth and final "100 
Hours of Astronomy" observing celebration. Here is what the sun looks 
like today  http://sohowww.nascom.nasa.gov/data/realtime-images.html

I'll be out at Monrovia's Library Park with two telescopes - one is my 
homemade (in John Dobson's telescope makring class) safe solar 
telescope. And the other is a small reftactor fitted with a special 
h-Alpha filter. 

The homemade telescope shows the sun in white light - this is how the 
sun looks to the unaided eye. The viewer sees the photosphere, or the 
apparent surface of the sun, which has a temperature of 6,000 Celsius. 
You can say this is the sun you can "see" or what you see through a 
projection onto a piece of paper.

The other is a telescope fitted with an h-Alpha filter, which shows just 
one wavelength of light -the red light of hydrogen (wavelength of 656.3 
nanometers). With this we see the next highest layer of the sun - the 
chromosphere (temperature between 6,000 and 20,000 C.) We need a filter 
to see this layer because the brighter photosphere layer below washes 
out the fainter chromosphere, just like a bright streetlight would wash 
out the light of a flashlight. What you see through an h-Alpha filter 
are ribbony dark colored filaments against the disk and prominences on 
the edge, many times longer than the diameter of the Earth!

I took these definitions from my writeup for the SOHO outreach website 
:-)  http://soho.nascom.nasa.gov/outreach/past/Sidewalk/

For those who venture out to Myrtle and Lime, you'll be rewarded, not 
only with some great solar views, but I am bringing an AMAZING 
collection of educational handouts. While they last, get 3-d  images of 
the sun in H-alpha, courtesy of the SOHO  - Solar and Heliospheric 
Observatory, some more from STEREO ( two space-based observatories, one 
ahead of Earth, the other trailing behind.  I also have lots of NASA 
lithographs of the sun. And just a very few additional 3-d cards from 
the SOHO/TRACE missions.  And plenty of IYA bookmarks.  First come, 
first get!  See you in a half hour!

Jane

PS the Sun will be the subject of my May What's Up podcast!

-- 
Jane Houston Jones
Monrovia, CA
34.2048N 118.1732W, 637.0 feet
http://www.whiteoaks.com
Old Town Astronomers:  http://www.otastro.org
My JPL What's Up podcast: http://solarsystem.nasa.gov/news/whatsup.cfm
Twitter: http://twitter.com/jhjones  http://twitter.com/CassiniSaturn