thumb|[[Mars, an example of a cold desert planet, seen by the Mars Orbiter Mission space probe]]
A desert planet, also known as a dry planet, an arid planet, or a dune planet, is a type of terrestrial planet that is arid at the surface level.
Deserts can be cold or hot, and even retain water, like Antarctica or the Sahara on Earth; however, desert planets are arid across their entire surface. Mars is a prominent example of a (cold) desert planet with a tenuous atmosphere.
But also other arid planets with atmospheres more as well as less dense have been identified as desert planets, like Venus
Habitability
A 2011 study suggested that not only are life-sustaining desert planets possible, but that they might be more common than Earth-like planets. The study found that, when modeled, desert planets had a much larger habitable zone than ocean planets.
In a 2026 study, computer calculations show that arid terrestrial planets may have unbalanced geologic carbon cycles due to runoff-limits to weathering, which can lead to a loss of habitability and runaway warming. Even if a given planet is in the Habitable Zone (HZ), it can transition to an uninhabitable state if it does not have enough initial surface water to balance outgassing and weathering fluxes. So a planet with less than 10% Earth's oceans (as comparison half of the Atlantic Ocean), couldn't keep a balanced carbon cycle, entering in a runaway warming state, being unlikely to be habitable. The minimum threshold of surface water required to maintain a balanced carbon cycle would be around 0.2–0.5 Earth’s oceans by mass.
Science fiction
The concept has become a common setting in science fiction, appearing as early as the 1956 film Forbidden Planet and Frank Herbert's 1965 novel Dune. The environment of the desert planet Arrakis (also known as Dune) in the Dune franchise drew inspiration from the Middle East, particularly the Arabian Peninsula and Persian Gulf, as well as Mexico. Dune in turn inspired the desert planets which prominently appear in the Star Wars franchise, including the planets Tatooine, Geonosis, and Jakku.
See also
- Exoplanet
- Ocean world