No. 96: Nov-Dec 1994
July 29, 1993. North Pacific Ocean. From the m.v. BP Admiral.
"At 1045 UTC a large, very well defined and complete halo was seen around the 10-day-old moon. Vertical angles were taken by sextant while horizonal angles were found by gyro repeater.
"...the area inside the halo was inky black with the inner edge of the halo being very clear cut and well defined; a 'spiked' effect was seen on the outer edge."
(Ronald, J.M.; "Halo," Marine Observer, 64:105, 1994.)
Comment. The angular diameter of the halo is normal, but the inky black interior is very rare. The same dark effect is sometimes seen between primary and secondary rainbows and has an acceptable explanation. However, the radial spokes are not accounted for by halo theory.