Which planets are terrestrial planets and which planets are gas giants?

Answer 1

Earth's solar system has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere.

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.

Plutoids, objects like Pluto, are similar to terrestrial planets in the fact that they do have a solid surface, but are composed of more icy materials

A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in our Solar System: Jupiter, Saturn, Uranus, and Neptune. Many extrasolar gas giants have been identified orbiting other stars.

Planets above 10 Earth masses are termed giant planets.[1] Below 10 Earth masses they are called super earths or, sometimes probably more accurately for the higher mass examples, "Gas Dwarfs" e.g. as suggested by MIT Professor Sara Seager[citation needed] for Gliese 581c using a model where that exoplanet was mostly composed of hydrogen and helium. The term "gas dwarf" was also used previously by others.[2][3]

Objects above 13 Jupiter masses are called brown dwarfs and these occupy the mass range between that of large gas giant planets and the lowest mass stars.