P^2 = (4π^2/G)(a^3) / (M)
where ε is the obliquity of the ecliptic (approximately 23.44°). spherical astronomy problems and solutions
The parallax method is used to measure the distances to nearby stars. The parallax is the apparent shift of a star's position against the background stars when viewed from opposite sides of the Earth's orbit. P^2 = (4π^2/G)(a^3) / (M) where ε is