Unformatted text preview: Note there is a geometrical magnication factor that helps: D = 0:72 :
So from dierent latitudes on one sees dierent tracks.
Separation is here
It is only
~ 1 Venus diameter.
Sun How to measure small separation from opposite sides of globe? Not by
subtracting measurements of height from \top" of sun | too imprecise.
Rather, take the average height to get the geometry, and use the dierence
of transit ingress/egress times or durations to infer the small dierences.
Order of magnitude (ignoring magnication factors, geometry, etc.): and diameters 12000 km 104 km
+ diameter 1:5 106 km 106 km + velocity 10 km= s ) 103 s to move diameter, 105 s 1 day to move across +
In 1761 and 1769 various discrepant results 10% were obtained. Not
until 1835 was an accurate value obtained (by Encke) from these same measurements: Gauss had, in the meanwhile, discovered least squares tting for
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- Fall '08