Talk:Solar eclipse of October 3, 1986

Observation claims[edit]

The comment that flying at 44,000 feet gets "80 miles" closer to the moon seems to be wrong; it's only 8+ miles of altitude. I also wonder about the comment about the size of the moon being 0.7 arc seconds when viewed from that height. That seems like too much of a change for such a relatively small fraction of the way from the Earth to the moon.

Someone should check the source and numbers. Agreed 44000' is 8.3 miles not 80. And I calculate arctan(8 miles/232000 miles) ~7 arc-seconds larger moon, not 0.7!? I calculate the moon was about 31.99' diameter from sea level near greenland, so it could be a larger ~32.1' near 44000', compared to the 31.97' diameter sun. Tom Ruen (talk) 23:09, 22 June 2011 (UTC)[reply]

I found a source [1], and geometric [2], showing how a 8 mile rise in elevation allows being 80 miles closer to the moon (due to the low elevation of the sun/moon). Tom Ruen (talk) 23:20, 22 June 2011 (UTC)[reply]

This article should be corrected to reflect the reality of observations by reliable sources. It was a partial eclipse with no period of totality whatsoever; not a hybrid as the calculations done in 1966 predicted. A number of individuals flying in a chartered Cessna Citation (account and photos of Bailey’s beads here) and who flew very close to the centerline (pre-GPS days) concluded that this was a very deep partial eclipse. The apex of the cone of totality (the true point of zero-duration totality, was above their flying altitude of 40,000 feet. Greg L (talk) 16:52, 21 June 2020 (UTC)[reply]

"The total solar eclipse of 3 October 1986 illustrates the effects of using different values of k [i.e. the mean lunar radius, expressed in units of the Earth's equatorial radius] in eclipse calculations. For example, the Fifty Year Canon predicts a maximum duration of totality of 0.2 seconds and a path width of 2.3 km (k=0.272281). However, the Astronomical Almanac for 1986 predicts a duration of 3.3 seconds and path width of 31.1 km (k=0.2725076). Experienced observers in the path reported that the eclipse was never quite total. Instead, Baily's Beads surrounded the Moon for several seconds during maximum eclipse. The symmetry of the beading phenomena in photographs proves that the observers were near the center line and not the edge of the path. Thus, predictions using the smaller 'k' are in better agreement with actual observations made near the center line." [Fifty Year Canon of Solar Eclipses: 1986-2035 by Fred Espenak, NASA, 1987, ISBN 0-933346-45-X, page 17]