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

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

(astronomy) A hypothetical type of planet resulting from the atmosphere and outer layers of a gas giant being stripped away, leaving the rocky, metallic core.

(broadcasting) The deliberate inclusion in broadcast media of messages warning about climate change or promoting environmental sustainability.

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.

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

Alternative form of exoplanet

Alternative form of hamplanet

plural of sun and planet gear

A device for converting reciprocating motion to rotary motion, used in the first rotative beam engines.