Observation in specific locations On this azimuthal equidistant projection centred on Mecca, when the subsolar point is on the Ka'bah, shadows of vertical poles on the sunlit hemisphere point away from it The subsolar point moves constantly on the surface of the Earth, but for any given time, its coordinates, or latitude and longitude, can be calculated as follows: The subsolar point crosses the Equator on the March and September equinoxes.Ĭoordinates of the subsolar point The subsolar point contacts the Tropic of Cancer on the June solstice and the Tropic of Capricorn on the December solstice. However, it will also move north and south between the tropics over the course of a year, so will appear to spiral like a helix. To an observer on a planet with an orientation and rotation similar to those of Earth, the subsolar point will appear to move westward with a speed of 1600 km/h, completing one circuit around the globe each day, approximately moving along the equator. It can also mean the point closest to the Sun on an astronomical object, even though the Sun might not be visible. The subsolar point on a planet is the point at which its Sun is perceived to be directly overhead (at the zenith) that is, where the Sun's rays strike the planet exactly perpendicular to its surface. ![]() ![]() Point which the sun is directly overhead The subsolar point at Honolulu during Lahaina Noon with the range of possible subsolar points shaded in pink – the angle between the Sun and the local horizontal level is exactly 90° at the subsolar point
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