The geology of solar terrestrial planets mainly deals with the geological aspects of four planets of the Solar System namely, Mercury, Venus, Earth, and Mars and one terrestrial dwarf planet, Ceres. Only one terrestrial planet, Earth, is known to have an active hydrosphere.
Terrestrial planets are substantially different from gas giants, which might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. These planets have a compact, rocky surfaces, with the last three also having an atmosphere. Their size, radius, and density are all similar.
Terrestrial planets have numerous similarities to plutoids (objects like Pluto), which also have a solid surface, but are composed of more icy materials. During the formation of the Solar System, there were probably many more (planetesimals), but they have all merged with or been destroyed by the four remaining worlds in the solar nebula.
Terrestrial planets all have roughly the same structure—a central metallic core, mostly iron, with a surrounding silicate mantle. The Moon is similar, but lacks an iron core. Three of the four solar terrestrial planets (Venus, Earth and Mars) have substantial atmospheres; all have impact craters and tectonic surface features such as rift valleys and volcanoes. The term inner planet should not be confused with inferior planet, which designates those planets which are closer to the Sun than Earth is (i.e. Mercury and Venus).
Other articles related to "geology of solar terrestrial planets, solar, planets, planet":
... sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 55 AU from ... Like the asteroid belt, it consists mainly of small bodies (remnants from the Solar System's formation) and at least one dwarf planet—Pluto ...
Famous quotes containing the words planets and/or solar:
“Perhaps when distant people on other planets pick up some wave-length of ours all they hear is a continuous scream.”
—Iris Murdoch (b. 1919)
“Senta: These boats, sir, what are they for?
Hamar: They are solar boats for Pharaoh to use after his death. Theyre the means by which Pharaoh will journey across the skies with the sun, with the god Horus. Each day they will sail from east to west, and each night Pharaoh will return to the east by the river which runs underneath the earth.”
—William Faulkner (18971962)