Climate of Pluto
[1] These climate zones are delineated based on astronomically defined boundaries or sub-solar latitudes, which are not associated with the atmospheric circulations on the dwarf planet.
Its surface is primarily composed of methane (CH4), nitrogen (N2), and carbon monoxide (CO) volatile ices in various spatial abundances and distribution.
[7][8] Long-term climate cycles of planetary bodies (e.g., Earth) are associated with axial precession and variations in the obliquity[9] and orbital eccentricity.
The permanent tropics always receive direct overhead sunlight during every orbital period of Pluto, and overall, they show the greatest range of albedo variation.
The high obliquity induced in latitude variations in arctic zones extending down to near-equatorial regions indicates that the maximum amount of insolation is received at the poles.
[11][15][16] The diurnal climate zone of Pluto is defined as the latitudinal ranges where day and night cycle occur for each rotation throughout the entire orbital year.
The high mean obliquity and oscillation cycle make a narrow latitudinal band experience a diurnal circle.
Pluto experiences the narrowest band of diurnal zone when the obliquity comes down to minimum of 103°, which occurred around ~0.8 million years ago.
[1] The present-day diurnal climate zone of Pluto spans from 30°N to 30°S, encompassing 50% of the total surface area, due to the current axial tilt of 120°.
As obliquity changes to rise from this value, the diurnal zone will expand to the maximum from 37°N to 37°S (covering a total area of 60%), which will be reached in roughly 600,000 years.
Only the latitude range between 37° and 53° in each hemisphere remains stable over the period, and therefore, those bands are called the permanent tropical arctic zones on Pluto (which covers 20% of the total area).
[1] The maximum extent of the tropical arctic zone spans between 13° and 77° latitude in both the southern and northern hemispheres (and covers about 75% of the total surface area).
The tropical arctic zone is the area that experiences maximum cyclical extremes and is optimum for long-term seasonal layering (e.g. al-Idrisi Montes).
[18] Pluto's polar zone comprises those areas where the Sun never reaches the zenith at any time of the orbital period of the dwarf planet over its entire obliquity cycle.
The absence of any interval of arctic winter darkness also precludes the possibilities of volatile cold trapping in the high-albedo diurnal zone.
[16][17] The temperature cycle near the equator (in the diurnal zone) maintains sharp albedo variations between the bright and dark regions.
