Terrestrial Planet

A terrestrial planet is a planet which has solid surfaces and is primarily composed of silicate racks and/or metals. There are 4 known terrestrial planets in our solar system – Mercury, Venus, Earth and Mars, which are all inner planets and one terrestrial dwarf planet, Ceres, located in the asteroid belt. These planets share similar characteristics such as proximity to the soon, few or no moons, absence of planetary rings such as Saturn’s, relatively weaker magnetic fields and closely spaced orbits. They are also relatively smaller compared to the ‘gas giants’ Jupiter, Saturn, Uranus and Neptune, which are located beyond the asteroid belt or “outer planets”.

Terrestrial planets have similar structures – a core composed of heavy metals which is usually iron, solid surfaces of craters, canyons, mountains and volcanoes and secondary atmospheres (generated through volcanic activity and comet impacts), as opposed to the gas giants which has primary atmospheres (captured directly from the original nebula). Note that while the moon has similar structure, it doesn’t have an iron core. Plutoids are also similar to terrestrial planets in that they have solid surfaces; but instead or rocky surfaces, they are composed of icy materials.

Mercury is one dense planet composed of iron and nickel, with a very thin atmosphere. Venus has a thick atmosphere, mostly of carbon dioxide, which causes a greenhouse effect. Earth has the highest density among these planets with an atmosphere composed of elements that are conducive for human habitation and Mars has a rocky red surface and a thin atmosphere. Note that among these 4, only Earth and Mars has moons; Earth has one and Mars has two). Extra-solar terrestrial planets are the subject of much interest, as people naturally want to know of the existence of other planets that are habitable for humans, or for the theoretical extraterrestrial beings.


    I’m in 6th grade and I have to do a project on a planet xP

  • makayla

    HI my name is makayla stokes i am in the 5th grade and i love the planets infact i just learned 7 words called rings,comet, galilean moon, the geart red spot,draf planet,methan, and triton.WOW WOW WOW!

  • planet sexy

    hey man planets are sexy they are soo cool snd fun to learn about..

  • Brianna101

    oh im 18 and in 12 th but great site helped learn wat all the planets havein common wit earth

  • Jonathan


  • Scene girl

    Hey guys im 16 and i need help with a problem what do i do if i really like this one guy but idk if he likes me back plus to make things worse he sits by me in Math write back if you know any good tips

  • E=MC squared (Earth=Mini Cheeseburgers squared)

    ps: im 9 years old (4th grade ) im also in T.A.G (Talented And Gifted program)

  • E=MC squared (Earth=Mini Cheeseburgers squared)

    einstien’s theory of relativity proves global warming in mars, mercury, and venus, but earth still stands.time itself is how.but why?well,global warming took the same amount of time,and they are in different levels of global warming.(earth 1st level,mars 2nd, venus 3rd, and mercury last. each is older, and all are scoching hot,so they had to have global warming

  • Joseph

    Hi, I dont know which grade i am, i mean, im not in AMERICA! Im in New Zealand and a 5 year student, yes still primary schoo, ok, I love earth, and all the planets, I just learnt about the sun forms. Can’t believe the sun is called “An Average Star!” Well I love your website and need to say that you ae the BEST. B E S T!

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    i love the planets

  • up yours

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  • Unknown

    Hi Im in 6th grade

    PS whats up : The SKY


  • http://planetfact.org wadley gaspard

    earth is cool!!!!!!!!!!!!!!!!!!! hi i’m in the 5th grade what’s up