Solar eclipse of October 3, 1986

A total solar eclipse occurred on October 3, 1986. It was a hybrid event (normally, an eclipse which is annular for most of its duration, but with totality either at the beginning, end or at sometime during the eclipse) that did not officially satisfy the definition of totality. Totality occurred for a very short time (calculated at 0.2 seconds) in an area in the Atlantic Ocean, just east of the southern tip of Greenland. The path, on the surface of the Earth, was a narrow, tapered, horse-shoe, and visible only from a thin strip between Iceland and Greenland. The eclipse's very short maximum duration was the result of the lunar and solar topocentically viewed diameters being virtually identical. At maximum eclipse the solar elevation was about 6°.

Observations

A single aircraft deployed to the region to intercept the eclipse at totality. By intercepting the umbral cone at 44,000 feet, they get closer to the moon by 80 miles relative to a sea level site, and grew the Moon's diameter with respect to the Sun by a 0.7 arc seconds. Calculations using a smooth lunar rim at the aircraft's altitude showed a possible 1.5 second maximum duration. This is reduced to negative 0.2 seconds when the true lunar rim is applied. The eclipse duration on the moving aircraft was estimated at between 5 and 6 seconds by the witnesses. At 44,000 feet, the eclipse was not annular, though some have argued it was not total as the photosphere was never instantaneously completely extinguished (as a Baily's beads - a diamond in the tiara - formed at the 3rd contact limb 0.2s before 2nd contact so that totality did not officially take place). The nine flyers who viewed this eclipse by air were rewarded to a ring of chromospheric light (a "diamond tiara" as opposed to the "diamond ring" effect usually seen at 2nd and 3rd contacts of a normal total eclipse).

Related eclipses

Solar eclipses of 1986-1989

This set of solar eclipses repeat approximately every 177 days and 4 hours at alternating nodes of the moon's orbit.

Metonic cycle

The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days).

Notes

References

• Earth visibility chart and eclipse statistics Eclipse Predictions by Fred Espenak, NASA/GSFC
  • Google interactive map
  • Besselian elements
• 03 October 1986: A Geometrically Remarkable Eclipse