Due to its lack of an atmosphere to retain heat, Mercury experiences extreme temperature fluctuations. While daytime temperatures can reach 430°C, nighttime temperatures drop significantly, reaching lows of approximately -180°C, though -125°C is often cited in general contexts as a representative extreme.

In our solar system, the planets are arranged in order of their distance from the Sun. Mercury is the closest planet, followed by Venus, which is the second planet. Venus is often referred to as Earth's twin due to its similar size and mass, though its atmospheric conditions are vastly different.

Viscosity is the measure of a fluid's resistance to gradual deformation by shear stress or tensile stress. In common terms, it is the 'thickness' or 'stickiness' of a liquid; for example, honey has a higher viscosity than water.

Magma that cools beneath the surface forms intrusive igneous rocks, while lava that cools on the surface forms extrusive igneous rocks. This process is fundamental to the formation of both the continental crust and the oceanic crust, which constitutes the sea floor.

The Mid-Atlantic Ridge is a divergent tectonic plate boundary located along the floor of the Atlantic Ocean. As the North American and South American plates move westward and the African and Eurasian plates move eastward, the seafloor spreads, causing the continents of America and Africa to gradually move further apart over geological time scales.

At divergent plate boundaries, tectonic plates move away from each other. In oceanic settings, this movement creates a gap or rift, which is subsequently filled by upwelling magma from the mantle, leading to the formation of new oceanic crust and mid-ocean ridges.

The South American Plate is primarily a continental plate, as it consists largely of the South American continent. While it does include a significant portion of the Atlantic Ocean floor, it is categorized as a continental plate because it carries the continental landmass.

The San Andreas Fault in California is a famous transform plate boundary. It marks the sliding contact between the Pacific Plate and the North American Plate, which move horizontally past each other, causing frequent seismic activity in the region.

Due to the higher density of oceanic crust compared to continental crust, when these plates collide, the oceanic plate is forced beneath the continental plate in a process known as subduction. This movement pushes the oceanic plate downwards into the mantle, often resulting in deep-sea trenches and volcanic arcs.

Plate Tectonics is the scientific theory describing the large-scale motion of the plates making up the Earth's lithosphere. These plates constitute the outermost shell of the Earth, known as the crust and the uppermost solid mantle.