<P> The subsolar point on a planet is where its sun is perceived to be directly overhead (in zenith); that is where the sun's rays are hitting the planet exactly perpendicular to its surface . It can also mean the point closest to the sun on an object in space, even though the sun might not be visible . </P> <P> For planets with an orientation and rotation similar to the Earth's, the subsolar point will move westward, circling the globe once a day, approximately moving along a circle of latitude . However, it will also move north and south between the tropics over the course of a year, so it is spiraling, like a helix . </P>

When does the sub solar point strike the most southerly point on the earth's surface