Geology of solar terrestrial planets of heavier elements contained in the solar nebula. The four inner or terrestrial planets have dense, rocky compositions, few or no moons, and no ring systems. They are composed largely of minerals with high melting points, such as the silicates which form their solid crusts and semi-liquid mantles, and metals such as iron and nickel, which form their cores. The Mariner 10 mission (1974) mapped about half the surface of Mercury. On the basis of that data, scientists have a first-order understanding of the geology and history of the planet. Mercury's surface shows intercrater plains, basins, smooth plains, craters, and
Solar eclipses on the Moon Earth rotates nearly 24 hours, but its position at the sky is only in one position as it never changes as it does with some other moons (or satellites) in other planets or dwarf planets and a few asteroids even inside the solar system but are very rare in the outer part of the solar system. The last solar eclipse on the Moon was a total eclipse on July 27, 2018, with the whole Nearside and the tiny surroundings of the Farside seeing totality. Unlike the Earth which sees its eclipse for up to 2 1/2 hours the longest in