# How can you determine the latitude of a place by observing the Sun at noon? When will you do this in Moscow in the summer?

The height of the Sun during the upper climax in the northern temperate latitudes is

h = 90 ° – ϕ + δ,

where ϕ is the geographical latitude of the observation site, and δ is the declination of the Sun, which is given in the “Astronomical Calendar” for every day. By measuring the height of the Sun at true solar noon, we can use this formula to determine the latitude of the place. However, at the same time you need to know the time of true solar noon, which differs from noon according to your watch and comes at

T0 = 12h + N – λ + η,

where N is the difference between standard and universal time, λ is the longitude of the place, expressed in hours, and η is the equation of time. In Moscow (λ = 2h31m) in summer N = 4, and true solar noon occurs at 13h29m + η. The value of the equation of time can also be taken in the “Astronomical calendar”, although in summer it does not exceed ± 6m.