Volcanism
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Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a heat source inside the body. This internal heat partially melts solid material in the body or turns material into gas. The mobilized material rises through the body's interior and may break through the solid surface.
A gentle, or effusive, volcanic eruption, in which liquid material (lava) gently flows from a vent, in this case in south-eastern Hawai’i island
The high initial temperatures of silicate lavas mean that they emit visible light before cooling.
Olympus Mons (Latin, "Mount Olympus"), located on the planet Mars, is the tallest known mountain in the Solar System.
Earth's internal heat budget
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Earth's internal heat budget is fundamental to the thermal history of the Earth. The flow of heat from Earth's interior to the surface is estimated at 47±2 terawatts (TW) and comes from two main sources in roughly equal amounts: the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of Earth.
Cross section of the Earth showing its main divisions and their approximate contributions to Earth's total internal heat flow to the surface, and the dominant heat transport mechanisms within Earth
Earth's tectonic evolution over time from a molten state at 4.5 Ga, to a single-plate lithosphere, to modern plate tectonics sometime between 3.2 Ga and 1.0 Ga