For this reason, the first four planets – Mercury, Venus, Earth, and Mars – are terrestrial planets. They are all small with solid, rocky surfaces. Meanwhile, materials we are used to seeing as ice, liquid, or …

Oct 21, 2025 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

Of the terrestrial (rocky) planets of the inner solar system, neither Mercury nor Venus have any moons at all, Earth has one and Mars has its two small moons. In the outer solar system, the gas giants Jupiter …

A fundamental issue of Solar System science is determining the early history of the terrestrial planets, including giant impact bombardment and the evolution of differentiated crust. Exploration and …

The early Moon may have developed an internal dynamo, the mechanism for generating global magnetic fields for terrestrial planets, but today, the Moon has a very weak magnetic field.

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Stray asteroids and asteroid fragments have slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.

May 28, 2025 · The first four planets from the Sun are Mercury, Venus, Earth, and Mars. These inner planets also are known as terrestrial planets because they have solid surfaces.

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Not only is it the largest moon in our solar system, bigger than the planet Mercury and the dwarf planet Pluto, but NASA’s Hubble Space Telescope has found the best evidence yet for an underground …