Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is componed primarily o silicate rocks or metals. Within the Solar Seestem, the terrestrial planets are the inner planets closest tae the Sun. The terms are derived frae Laitin wirds for Yird (Terra an Tellus), as these planets are, in terms o componeetion, "Earth-like".
Terrestrial planets hae a solid planetary surface, makin them substantially different frae the much lairger gas giants, which are componed maistly o some combination o hydrogen, helium, an watter existin in various pheesical states.
Astronomers at the Harvard-Smithsonian Center for Astropheesics (CfA) reportit in Januar, 2013, that "at least 17 billion" Yird-sized exoplanets are estimatit tae reside in the Milky Way Galaxy.[1]
References
[eedit | eedit soorce]- ↑ Staff (7 Januar 2013). "17 Billion Earth-Size Alien Planets Inhabit Milky Way". Space.com. Retrieved 8 Januar 2013.CS1 maint: uises authors parameter (link)