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 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.

plural of rocky planet

(obsolete, Britain, thieves' cant, derogatory, rare) Ireland.

(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.

(engineering) An epicyclic gear; the middle gears in a planetary gear system, spun by the central sun gear

plural of planet gear

plural of exo-planet