(astronomy) a planet that shares similar physical characteristics, such as size, density and mass, with another planet

(astronomy) Synonym of carbon planet

(astrology, astronomy) The seven non-fixed astronomical objects in the sky visible to the naked eye that where known in Ancient history

(astrology) A planet thought to bring bad luck to those born within its radius

Used other than figuratively or idiomatically: see tertiary, planet. (the third planet; usually counting outwards from the central sun)

Synonym of planet-struck

(astronomy, celestial mechanics) An imaginary celestial body (corresponding to another, real, orbiting one) which orbits with constant speed along an auxiliary circle (a circle which shares a diameter with the major axis of the elliptical orbit of the corresponding real celestial body), such that its position coincides with the position of the corresponding, real celestial body when that body passes through periapsis.

(astronomy) a body comparable to a planet, but not a planet, such as a dwarf planet or a planetary-mass moon

(astronomy) A planet composed primarily of metals and/or silicate rocks and having a solid surface.

There is only one Earth, so humans must do everything they can to conserve Earth's environment now, i.e. by taking steps to mitigate climate change, etc.