Find the current subsolar point:

Compute the sublunar point on this date:

Find which point on Earth has Mars on its zenith on this date:

Check that the altitude of Mars, as observed from this location on that date, is 90 degrees:

Use AstroSubpoint with any astronomical entity:

Compute the current subpoint of the solar system barycenter:

Compute the subpoint of a location on the surface of the Moon:

Compare to the sublunar point, the subpoint of the center of the Moon:

Compute the subsolar points during a year at the same time of the day:

They form an analemma:

Compute the subpoint of an astronomical object for a given date:

That object will have an altitude of 90 degrees when observed from that location on that date:

The subpoint of the star Polaris is close to the North Pole:

For a given date, compute the equatorial coordinates and the subpoint of an astronomical object:

The declination of the object coincides with the latitude of its subpoint:

The right ascension of the object does not coincide directly with the longitude of its subpoint:

The difference is given by Greenwich Sidereal Time:

The latitude limits of the subsolar point define the Tropics of Cancer and Capricorn:

Compute the subsolar point on a given date:

The solar time at that moment from that location is always noon: