Anyone who wishes to save the environment with an ambitious plan.

(astronomy, planets) Any planet of the Solar System whose orbit is located between the asteroid belt and the sun, i.e., any of Mercury, Venus, Earth, or Mars.

(astronomy) Any planet of the Solar System whose orbit is located beyond the asteroid belt, i.e., any of Jupiter, Saturn, Uranus, or Neptune.

(astronomy) An astronomical object in direct orbit around the Sun that is not a planet or a comet.

Alternative form of exoplanet

Any planet of the solar system or any exoplanet which is "Earth-like" in the sense that it is composed primarily of metals and rock, in contrast to a planet which is a gas giant.

(astronomy) A planet which orbits in the habitable zone around a star, where temperatures like those on Earth occur, allowing for the possible existence of liquid water and of life.

the planet Mars

Any of the four gas giant planets in the Solar System: Jupiter, Uranus, Saturn, or Neptune.

(astronomy) A world-like planetoid of the Solar system, that is smaller than the classical planets. More specifically, any astronomical body which has a geology defined by hydrostatic equilibrium (and thus has taken the shape a body of water would take, as opposed to a small Solar System body), orbits the Sun (as opposed to a moon), and does not gravitationally dominate other bodies near its orbit (as opposed to a classical planet or, in IAU usage, as opposed to a planet).