Easter Island
11 Jul 2010
Total Eclipse on Easter Island!
Critical Information Update Feb 2008
Please read this update NOW - important news for anyone seeking to go with us
I have been working with one tour company who is planning an eclipse expedition to Easter Island for this eclipse.
Easter Island lies right smack dab in the path of totality! The latest chart I have is from Fred Espenak, and I've run some very unofficial, unscientific maps to try and find something
out about the length of totality. There are better charts
and maps
out there, but I can confirm that we'll definitely be getting a total eclipse!
Easter Island seems to lie just south of the centerline,with the line itself almost paralleling the slight NW -
SE curve of the island's NE shore. The shadow gets to the western edge of the island about 20:11UT (3:11pm local),
and takes about 20 seconds to get to the eastern edge. Totality on the centerline at that point is about 4m49s,
but since the island is between 4-14 miles off the centerline (south of it), you lose some of that. Not much, because
the path is MUCH MUCH wider than the island itself, so you don't get a lot of the totality loss that happens near
the edge of the path. I'd guess between 4m40s and 4m45s.
An interesting fact I saw in the mapping was that in the 14 years that elapsed between the time Espenak published
his 50-year Canon, and the latest table on his website, the value of delta-T that he used decreased from 73.4s
to 67.1s. (Google "delta T eclipse" if you want the nitty gritty on what this is. It has to do with the
predictions astronomers have to make regarding the erratic nature of the earth's rotation, and how much it differs
from a uniformly-rotating, "mean" earth...I think.) The long and short of it is that the projected path
of the eclipse has been shifted south and west just slightly from the prediction in 1987 to the prediction in 2004.
That means that, even though Easter Island is now projected to be slightly closer to the centerline, it is now
farther east along the actual shadow path, and so the effects on totality duration are somewhat offsetting.
I think I'll be happy just saying "we'll get about 4m45s", and let the computer guys come up with the
details. The weather is much more important anyway!
