European Southern Observatory (ESO)European Association for Astronomy Education (EAAE) Observatoire de ParisInstitut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE)Astronomical Institute of the Academy of Sciences of the Czech Republic The Venus Transit 2004 European Science & Technology Week 2004Visit the websites of the VT-2004 organisers

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