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The Venus Transit 2004
... Educational Sheet 3
Appendix 3
Parallax of the Sun (the horizontal parallax)
By definition, the parallax of the Sun is the angle β shown below
By trigonometry, tan β = R / r but the angle β is small and tan β can be approximated by β, measured in radians. R is the radius of the Earth and r is the distance from the Earth to the Sun. We can calculate r using the relationship
r = R / β
More details can be found in the EduSheet 2
Back to the EduSheet 3