inner planet

[in-er plan-it]

noun

Astronomy.

1. any of the planets in our solar system whose orbits lie between the sun and the asteroid belt, namely, Mercury, Venus, Earth, and Mars, all of which are terrestrial planets.

inner planet

noun

1. any of the planets Mercury, Venus, earth, and Mars, whose orbits lie inside the asteroid belt

inner planet

1. 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.

2. Also called terrestrial planet

3. Compare outer planet See also inferior planet

Word History and Origins

Origin of inner planet¹

First recorded in 1950–55