inner planet
noun Astronomy.
any of the four planets closest to the sun: Mercury, Venus, Earth, or Mars.
Also called
terrestrial planet.
Compare
outer planet.
Origin of inner planet
First recorded in 1950–55
Words nearby inner planet
inner jib,
inner light,
inner man,
inner mission,
inner mongolia,
inner planet,
inner product,
inner sanctum,
inner space,
inner temple,
inner tube
British Dictionary definitions for inner planet
inner planet
noun
any of the planets Mercury, Venus, earth, and Mars, whose orbits lie inside the asteroid belt
Scientific definitions for inner planet
inner planet
Any of the four planets Mercury, Venus, Earth, and Mars, whose orbits lie nearest the Sun. The inner planets are of similar size and have high densities compared to the larger gas giants among the outer planets. They are composed mostly of rock and metal and are relatively slow to rotate, with solid surfaces, no rings, and few moons. Also called terrestrial planet Compare outer planet. See also inferior planet.