Spherical Earth

[1] The Solar System formed from a dust cloud that was at least partially the remnant of one or more supernovas that produced heavy elements by nucleosynthesis.

Though the surface rocks of Earth have cooled enough to solidify, the outer core of the planet is still hot enough to remain liquid.

Energy is still being released; volcanic and tectonic activity has pushed rocks into hills and mountains and blown them out of calderas.

However, if the energy release from these processes halts, then they tend to erode away over time and return toward the lowest potential-energy curve of the ellipsoid.

Weather powered by solar energy can also move water, rock, and soil to make Earth slightly out of round.

Greek ethnographer Megasthenes, c. 300 BC, has been interpreted as stating that the contemporary Brahmans of India believed in a spherical Earth as the center of the universe.

[5][6][7][8] A practical demonstration of Earth's sphericity was achieved by Ferdinand Magellan and Juan Sebastián Elcano's circumnavigation (1519–1522).

Other speculations on the shape of Earth include a seven-layered ziggurat or cosmic mountain, alluded to in the Avesta and ancient Persian writings (see seven climes).

The roughly spherical shape of Earth can be empirically evidenced by many different types of observation, ranging from ground level, flight, or orbit.