The inner planets of the solar system are all relatively close to the sun. They are also all relatively similar to each other in size, mass, density and other physical properties. Unlike the outer planets, the inner planets are small, dense and warm.Know More
The four inner planets of the solar system are, in order, Mercury, Venus, Earth and Mars. All four of these worlds are small compared with the four gas giants that are the outer planets, and they are relatively dense. The four inner planets are much closer to the sun than the outer planets, so they receive considerably more light and are consequently much warmer. None of the four inner planets have rings, while all four outer planets do.
In contrast to the gas planets, the four terrestrial planets all have thin, tenuous atmospheres. Planetary atmospheres can be either reducing, which means dominated by hydrogen, or oxidizing. The inner planets have oxidizing atmospheres, as the solar wind long ago blew the light hydrogen gas away from their surfaces. Their thin atmospheres and close proximity to the sun give the inner planets wide temperature ranges. Unlike Jupiter, which maintains a fairly stable temperature from the daytime side of the planet to the night, the terrestrial planets are significantly colder on their night sides than on the hemispheres facing the sun.Learn more about Planets
The inner planets are composed of rock and metals, and possess a solid surface not found in the gas giants of the outer solar system. Mercury, Venus, Earth and Mars are the four planets closest to the Sun, and all have molten metal cores and few moons.Full Answer >
The surface temperatures of the solar system's planets are dependent on how close each planet is to the sun. Planets that have atmospheres are better able to retain heat from the sun, affecting the planet's surface temperature.Full Answer >
The main reason planets in the solar system can be seen from Earth is because they reflect light from the sun. The light reflected off of the five closest planets, Mercury, Venus, Mars, Jupiter and Saturn, can be seen from the Earth with the naked eye.Full Answer >
In order to be declared a planet, a celestial body must meet the following qualifications: It must orbit the sun, it must maintain a nearly spherical shape and have the necessary mass for self-gravity so that it does not succumb to rigid body forces, and it must clear the neighborhood around its orbit. All recognized planets in the solar system meet this definition.Full Answer >