Re: [Plplot-devel] <off topic> Solar eclipse coming for North America in 4 days!

[Alan W. I. <ir...@be...>]

I would add to Steve's points that although total solar eclipses
tracks often occur on the Earth those tracks are extremely narrow and
of relatively short duration so observing a total solar eclipse from a
fixed Earth location is a rare event (typically 3 times per thousand
years according to a pamphlet I have in front of me.) Despite the
improbability for one such event, Carbondale, Illinois will observe
two (!) total solar eclipses in the next 7 years (in 4 days when it
will be near the maximum totality point of the totality track that
occurs close to the middle of the longitude range of the track, and
also on April 08 2024 where again it will be close to the maximum
totality point).  There is a birthday paradox occurring here so you
have to be careful about getting too wild about improbability claims
for such double solar eclipes in 7 years or less for any fixed
location on Earth since all you need for such an event to occur is two
totality tracks crossing each other in 7 years or less.

I am sure somebody has made that calculation considering what is going
on for Carbondale in the next 7 years, and maybe narrowing it even
further by constraining the calculation so that the crossing occurs
near the maximum (say from the 45 per cent point to the 55 per cent
point of the track) of each totality track.  I haven't yet found such
a calculation, but I am sure such crossings near the totality maximum
for each don't occur very often. So Carbondale, Illinois is clearly
going to be "the" lucky total solar eclipse location for quite some
time before some other point on Earth inherits that designation.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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