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Galaxy Club

Great American Total Solar Eclipse, 2017

On August 21, 2017, it is estimated that over 40 million Americans will witness one of nature's splendors, a total solar eclipse!  The last eclipse of this kind in the country was in 1979 and the last coast-to-coast eclipse was on June 8, 1918!  The 70 mile wide shadow of the Moon will cross from Oregon, through southern Illinois, and on to South Carolina on Monday afternoon, August 21, completely covering the Sun for 2 minutes, 39 seconds. 







"Why is this happening?"


The Moon orbits our Earth roughly once a month, which is our basis for the month.  During new Moon the Moon is in the same general direction as our Sun but the Moon's orbit it tilted five degrees.   This isn't much but it is enough for us to see the Moon usually pass above or below our Sun, hence we don't have one solar and one lunar eclipse each month.  The Moon is 400 times smaller than the Sun but it is also 400 times closer to us.  Thus they appear roughly the same size in our sky.  Most of the time the Moon's shadow misses our Earth.   A couple of times per year it strikes our Earth, but observers have to be in that shadow to see the eclipse.  If you miss this eclipse, you'll have to wait until April, 2024 for the next one! 


"If I stay in Champaign County, what will I see?"


At 11:53am the Moon will begin to cover the Sun.  Maximum coverage occurs at 1:20pm on August 21, but only 93% of the Sun will be covered.   CAUTION:  7% of the Sun can still blind you!!  The event will be over by 2:44pm.  Note that there are no events occurring at the Staerkel Planetarium on this day.   The staff will watch the eclipse from southern Illinois. 


"Where can I go to get a good view?"


Southern Illinois is the place to be and NASA is actually setting up shop in Carbondale.   The University of Illinois Astronomy Department is heading to Goreville, IL.  The Staerkel Planetarium, CU Astronomical Society, and Twin City Amateur Astronomers are heading to Camp Ondessonk, near Ozark, IL. It is a 3.5 hour drive down I-57.  And you can join us if you wish!   There is a fee but that includes meals.   See the last bullet below under "useful links." 


"But you should never look at the Sun, how can you see this event safely?"


True, never look at the Sun without appropriate protection.  Sunglasses are NOT appropriate protection!!   There are ways to see the eclipse safely:

  • Purchase some mylar eclipse glasses (both the Staerkel Planetarium and the CUAS have these for sale to the public)
  • Use a #14 welders glass
  • If you use a telescope solar filter, be sure the filter covers the end of the telescope!   Filters that thread into a telescope's eyepiece should NOT be used!  They are unsafe!
  • Build a "sun funnel" to be used with a telescope.   Aim the telescope at the Sun using its shadow. 
  • Project an image of the Sun with a telescope or binoculars by placing an index card 6-8 inches beyond the eyepiece.  Again, use the instrument's shadow to point to the Sun. 
  • Build a pin-hole projector either using two sheets of card stock paper or with a shoebox


Useful links: