ECLIPSE SUBSTITUTION METHOD

July 11, 1991 Total Solar Eclipse Baja Mexico

Time of Mid-Eclipse: ..................12:01:00 Local Time(19:01:00UT)

Distance of Earth from Sun..............................94,496,400+1000Miles(A)

Distance of Moon from Earth...........................222,264 Miles(B)

Distance of Moon from Sun (A-B)...................94,274,136+1000Miles(C)

Length of Moon's Shadow

(C)/399.64814 (Last Constant).........................235,892.84 Miles(D)

Distance of Moon to Observation Site..............222,280+20Miles(E)

Moon's Shadow Extension into the Earth(D-E)......................................................13,603.84 Miles (F)

Linear Diameter of Moon's Shadow

(F/D x 2160 Moon's Diameter)........................124.5663 Miles(G)

Projected Diameter of Moon's Shadow

on the Earth....................................................143.815 Miles(H)

Speed of Moon's Shadow in Orbit..................2,289 MPH (I)

Speed of Moon's Shadow @ Observation Site

Speed of Moon minus Rotation of Earth..........1293 MPH(J)

Speed of Moon's Shadow

@ Observation Site.........................................21.55MPM (K)

Speed of Moon's Shadow

@ Observation Site.........................................0.359 MPS (L)

Duration Of Totality (H/L)...............................400.6 Seconds

Add 3 seconds moving in direction of the Moon's shadow @ 17 Knots