How is parallax calculated?

1 Answer
Apr 13, 2018

See below


There is two parallax to be calculated: the daily and yearly parrallax

Daily parallax is used to measure distance to satelites and is calculated as follows #p´´=a·sigma/(Dsin1´´)# where a is mayor semi axis Earth-Sun, D the distance to satelite from Earth, #sigma# is a correcction due to no sphericity of Earth and #p´´# is given in seconds of arc.

The yearly parallax is used to calculate distance to starts and in calculated by

#p´´=(lambda+omega-lambda+omega)/2# where #lambda, omega# are respectively the longitude of Earth and star in ecuatorial coordinates in the rigth moment they differ in 90º or 270º