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

Alternative form of protoplanetary

Unable to leave a planet

Airsick from travelling in an airplane.

(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.

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

Alternative form of hamplanet

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.