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 planetSee also inferior planet

Word History and Origins

Origin of inner planet¹

First recorded in 1950–55

Example Sentences

With that likelihood in mind, the group concludes that this plentiful type of inner planet could host alien microbes, and that any lifeforms on these worlds would alter their atmospheres in ways that astronomers will soon be able to detect with ease.

From Popular-Science

Rather, the garden-variety inner planet seems to fall somewhere between a rocky dwarf and a gassy giant.

From Popular-Science

The solar system’s inner planets, including Earth, could instead have formed through big collisions, he suspects.

From Science News For Students

Researchers are still working out the details of why this happens, but the general theory is that inner planets tend to run hotter, which boils away their gassy atmospheres, leaving mainly rocky cores behind.

From Popular-Science

The flow of gas changes and creates a pileup interior to the inner planet’s orbit, which acts to push both planets outward.

From Nautilus

Meadows began to play inner planet combinations that occasionally paid, though at short odds.

From Project Gutenberg

"The most probable one is the next inner planet, Aphrodite," replied Morey.

From Project Gutenberg

The inner planet revolved about it with one side glowing low red heat and the other side piled high with frozen atmosphere.

From Project Gutenberg