---
title: Temperate gas giant
canonical_url: https://paxabyssi.com/wiki/Temperate_gas_giant
markdown_url: https://paxabyssi.com/wiki/Temperate_gas_giant.md
type: wiki-page
revision_id: 578
revision_view: stable
last_updated: 2026-09-28
license: CC BY-SA 4.0
license_url: https://creativecommons.org/licenses/by-sa/4.0/
science_status:
  - observed
  - model
  - sim
summary: A gas giant warmer than Jupiter but cooler than a hot Jupiter, roughly 150 to 700 K, where ammonia clouds give way to water clouds and then to clear air. It spans the widest range of looks of any giant, from brilliant white to dark blue, and Pax Abyssi draws eight types across it.
categories:
  - Gas giants
  - Planet classes
  - Giant planets
aliases:
  - Temperate gas giants
  - GGT
  - G3-T
  - Warm Jupiter
  - Warm Jupiters
  - Warm giant
  - Water-cloud giant
  - Clear-blue giant
  - Hazy giant
  - Transition giant
  - GGT-TN
  - GGT-WC
  - GGT-CB
  - GGT-HZ
infobox:
  type: planet_class
  code: GGT
  mass:
    note: "Pax Abyssi: log-normal about 1 M_Jup, 0.16 to 11"
    unit: M_Jup
    value: about 0.1 to 13
    source: observed
  name: Temperate gas giant
  image: File:Pax_giant_GGT-WC-PB-2_phase70.webp
  level: Type
  radius:
    unit: R_Jup
    value: about 0.8 to 1.2; not inflated
    source: observed
  series: G (gas giant)
  caption: "In Pax Abyssi: a Pale Banded water-cloud giant (GGT-WC-PB) half lit by its star, white water-ice zones over pale blue belts"
  subtypes: GGT-TN Transition (FD, EM), GGT-WC Water-Cloud (BW, PB), GGT-CB Clear-Blue (AZ, DP), GGT-HZ Hazy (SM, TN)
  sim_source: Temperate gas giant physics engine and properties module; the temperate giant science reference; the procedural gas giant generator
  bond_albedo:
    note: "Pax Abyssi: WC 0.55 to 0.81, TN 0.45 to 0.65, HZ 0.15 to 0.30, CB 0.10 to 0.20"
    unit: dimensionless
    value: 0.10 to 0.81 (models)
    source: model
  legacy_code: G3-T
  rings_moons: Moons possible at the outer end; Hill spheres shrink closer in
  tidal_state: Mostly not tidally locked; eccentric orbits common
  last_verified: 2026-09-28
  real_examples: HD 80606 b (highly eccentric); WASP-80 b (825 K, methane, at the hot boundary); directly imaged GJ 504 b (about 510 K) and 51 Eridani b (600 to 750 K) have effective temperatures in this range
  typical_orbit: About 0.1 to 1 AU around Sun-like stars (periods of weeks to about a year); closer around M dwarfs
  dominant_gases: H2 and He; methane the main carbon carrier below about 800 K; water vapour; ammonia
  science_status: observed (warm Jupiters' orbits, masses, radii, some spectra); model (clouds and colour); sim (subtypes)
  frequency_in_sim: 260 of the 8,742 planets in the 5,159 generated systems (TN 149, HZ 73, CB 30, WC 2)
  rendered_example: All eight types in the specimen gallery below; 16 looks in the gas giant generator
  defining_criteria: "Pax Abyssi: equilibrium temperature 150 to 700 K. Subtypes by temperature and haze: Transition 150 to 250 K, Water-Cloud 250 to 350 K, Clear-Blue 350 K and above with haze optical depth below 0.05, Hazy the same with more haze"
  interior_structure: As for cold giants; radius not inflated, so radius and mass together reveal the heavy-element content
  literature_equivalent: Warm Jupiter (orbital periods of roughly 10 to 200 days); Sudarsky classes II and III
  cloud_and_haze_species: NH3 fading at the cool end; H2O ice clouds near 250 to 350 K; none in the upper atmosphere above about 350 K except photochemical haze
  equilibrium_temperature:
    unit: K
    value: 150 to 700
    source: sim
related:
  - https://paxabyssi.com/wiki/Hot_Jupiter.md
  - https://paxabyssi.com/wiki/Cold_gas_giant.md
  - https://paxabyssi.com/wiki/Gas_giant.md
  - https://paxabyssi.com/wiki/Sudarsky_classification.md
  - https://paxabyssi.com/wiki/Ice_giant.md
  - https://paxabyssi.com/wiki/Barren_rock_world.md
---

# Temperate gas giant

> Source: https://paxabyssi.com/wiki/Temperate_gas_giant
>
> Licence: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/). Text by Pax Abyssi Wiki contributors; history at https://paxabyssi.com/wiki/Temperate_gas_giant/history
>
> Revision 578, 28 September 2026

A **temperate gas giant** is a giant planet warmer than Jupiter but cooler than a [hot Jupiter](https://paxabyssi.com/wiki/Hot_Jupiter.md), with an equilibrium temperature of roughly 150 to 700 K. Around a Sun-like star such planets orbit from about 0.15 AU out to a little beyond 1 AU, with years of a few weeks to a few years; astronomers call the inner ones **warm Jupiters**. This is the temperature range in which a giant's clouds change most. Ammonia clouds thin and disappear, water clouds form, and then the water evaporates too, leaving the upper atmosphere clear. The [Sudarsky classification](https://paxabyssi.com/wiki/Sudarsky_classification.md) predicts that the same planet moved inward through this range would turn from a brilliant white to a dark, featureless blue, which gives temperate giants the widest range of looks of any giant. Pax Abyssi draws that whole sequence, and every type in it is shown below.

## How Pax Abyssi classifies temperate giants

Across this range the question that decides a giant's look is which cloud, if any, sits on top, and that is set by temperature first and by haze second. The physics engine computes each planet's equilibrium temperature and the thickness of its photochemical haze, the smog that ultraviolet starlight makes from methane, and the subtype follows:

| Subtype     | Code   | Equilibrium temperature                        | Top of the atmosphere                        | Bond albedo  | Types                                                 |
| ----------- | ------ | ---------------------------------------------- | -------------------------------------------- | ------------ | ----------------------------------------------------- |
| Transition  | GGT-TN | 150 to 250 K                                   | Ammonia cloud thinning, water cloud starting | 0.45 to 0.65 | Fading Ammonia (FD, below 200 K), Emerging Water (EM) |
| Water-Cloud | GGT-WC | 250 to 350 K                                   | A deck of water-ice cloud                    | 0.55 to 0.81 | Brilliant White (BW), Pale Banded (PB)                |
| Clear-Blue  | GGT-CB | 350 K and above, little haze                   | No cloud high up                             | 0.10 to 0.20 | Azure (AZ, to 500 K), Deep Blue (DP, above 500 K)     |
| Hazy        | GGT-HZ | 350 K and above, haze optical depth above 0.05 | Photochemical haze                           | 0.15 to 0.30 | Smoky Blue (SM), Tawny Haze (TN)                      |

The Transition and Water-Cloud giants are the cool half of the sequence, Sudarsky's Class II world of water cloud; Clear-Blue is his Class III; Hazy is Class III under the haze his 2000 models left out [1] [2]. The type then follows the details: whether the new water cloud has spread across the planet or is still breaking through in patches, whether the water deck is thick enough to hide the bands, whether the clear air is warm enough to turn navy, and how thick the haze lies.

![A grey-cream gas giant with washed-out pale bands.](https://media.paxabyssi.com/public/e84ff3b473b7b9327d5b63fb5b9009978f3a9cbf54d5abce6ca570bb51afc912/900.webp "GGT-TN-FD · Fading Ammonia: Bleached cream bands on a grey-cream globe: above about 150 K the ammonia cloud forms deeper and thins, and no water cloud has yet taken its place.")

GGT-TN-FD · Fading Ammonia: Bleached cream bands on a grey-cream globe: above about 150 K the ammonia cloud forms deeper and thins, and no water cloud has yet taken its place. Credit: Pax Abyssi.

![A white gas giant crossed by torn grey streamers and patches of cloud.](https://media.paxabyssi.com/public/750ac3baa3db71696b6a182fc079b6423f8614d05412813cef9b87fd6015f711/900.webp "GGT-TN-EM · Emerging Water: Brilliant white water-ice cloud spreading across a grey planet, the last grey patches drawn out into streamers by the jets: near 200 to 250 K, water starts to condense high enough to become the top cloud.")

GGT-TN-EM · Emerging Water: Brilliant white water-ice cloud spreading across a grey planet, the last grey patches drawn out into streamers by the jets: near 200 to 250 K, water starts to condense high enough to become the top cloud. Credit: Pax Abyssi.

![A brilliant white gas giant with no visible features.](https://media.paxabyssi.com/public/fefff52669b1bd708bee6343feb7960bc656bde1014c8ee26ca6ad4488827ab0/900.webp "GGT-WC-BW · Brilliant White: Near-uniform brilliant white: a thick deck of water-ice cloud reflects most of the light that reaches it, and Sudarsky's model for this class reflects 81 per cent.")

GGT-WC-BW · Brilliant White: Near-uniform brilliant white: a thick deck of water-ice cloud reflects most of the light that reaches it, and Sudarsky's model for this class reflects 81 per cent. Credit: Pax Abyssi.

![A white gas giant with soft pale blue bands.](https://media.paxabyssi.com/public/8914589f6a6cfa9d64978bc598d0eafb0e213504178ea67510c0cd0bf9f165d4/900.webp "GGT-WC-PB · Pale Banded: White zones and pale blue belts: where drier air sinks, the water cloud thins and the blue light scattered by the clear hydrogen above shows through.")

GGT-WC-PB · Pale Banded: White zones and pale blue belts: where drier air sinks, the water cloud thins and the blue light scattered by the clear hydrogen above shows through. Credit: Pax Abyssi.

![A vivid azure gas giant with no bands or storms.](https://media.paxabyssi.com/public/2e51e745b6bfad171685e9f1907bc79d1cc23e7d80ea20e5f37a876e81b38c61/900.webp "GGT-CB-AZ · Azure: Vivid, featureless azure: above about 350 K nothing condenses high in the atmosphere, so hydrogen scatters blue light back to space while methane absorbs the red.")

GGT-CB-AZ · Azure: Vivid, featureless azure: above about 350 K nothing condenses high in the atmosphere, so hydrogen scatters blue light back to space while methane absorbs the red. Credit: Pax Abyssi.

![A dark navy-blue gas giant with no visible features.](https://media.paxabyssi.com/public/f41c9aad0fdb3ba5525ad7c340e5224d34e37e1c0d4208eed89c567460397948/900.webp "GGT-CB-DP · Deep Blue: A dark, featureless navy: in a warmer clear atmosphere more of the red and near-infrared light is absorbed on its way in, and little returns.")

GGT-CB-DP · Deep Blue: A dark, featureless navy: in a warmer clear atmosphere more of the red and near-infrared light is absorbed on its way in, and little returns. Credit: Pax Abyssi.

![A muted grey-blue gas giant with faint soft bands.](https://media.paxabyssi.com/public/ae498061e5f3c1ada929541420ac8509160ea3c7224295f520a1b1edc9a8bba8/900.webp "GGT-HZ-SM · Smoky Blue: Blue seen through smoke: a thin photochemical haze, made when ultraviolet starlight breaks up methane high in the atmosphere, greys and softens the clear-sky blue.")

GGT-HZ-SM · Smoky Blue: Blue seen through smoke: a thin photochemical haze, made when ultraviolet starlight breaks up methane high in the atmosphere, greys and softens the clear-sky blue. Credit: Pax Abyssi.

![A tawny brown gas giant with no visible features.](https://media.paxabyssi.com/public/1c6d9f014f06695f64631e17553bc2087ff8104eebedaa9170cd02bb698cb2b7/900.webp "GGT-HZ-TN · Tawny Haze: A tawny, featureless globe: a thick haze absorbs blue light and scatters warmer colours, burying the blue beneath it.")

GGT-HZ-TN · Tawny Haze: A tawny, featureless globe: a thick haze absorbs blue light and scatters warmer colours, burying the blue beneath it. Credit: Pax Abyssi.

*Figure 1.* In Pax Abyssi: all eight temperate gas giant types, cool to warm, drawn by our gas giant generator with the same shaders the game uses. Every giant also draws its own seed, and the commonest types have extra variants.

## Characteristics

### From ammonia to water to clear air

The clouds a giant shows depend on which gases can condense in its upper atmosphere (see [Cold gas giant](https://paxabyssi.com/wiki/Cold_gas_giant.md) for the three decks of Jupiter and Saturn). As a giant warms past about 150 K, the ammonia deck forms deeper and fades from view. Around 250 K, in the models, water condenses high enough to become the top cloud, and a giant covered in water-ice cloud would be the most reflective planet of any kind: Sudarsky's Class II model reflects 81% of the light that reaches it [1]. It would look like a larger, whiter Venus with faint pale-blue bands and none of Jupiter's browns, because the coloured compounds that stain Jupiter's belts form above or among ammonia clouds, not water.

Above about 350 K, water no longer condenses in the upper atmosphere. Starlight penetrates deep. Hydrogen molecules scatter blue light back out, and sodium, potassium, methane and water absorb the red and near-infrared, so the model planet turns dark and blue, reflecting only about 12% of the incoming energy around a Sun-like star [1]. With no cloud tops to trace the winds, it would look nearly featureless. Photochemical hazes, made by ultraviolet light breaking up methane and other molecules high in the atmosphere, can dull that blue toward grey or brown, and later models show how haze, metallicity and viewing angle move the colours of such planets around [2].

### Normal sizes, useful densities

Many hot Jupiters are inflated beyond Jupiter's size by heat deposited in their interiors, but the effect switches off below an orbit-averaged stellar flux of about 2 × 10⁸ erg s⁻¹ cm⁻², roughly 150 times the sunlight Earth receives and an equilibrium temperature near 1,000 K [3]. Temperate giants therefore have the radii their mass and composition predict. That makes them the best giants for weighing heavy elements: comparing a warm giant's measured mass and radius with structure models reveals how much rock and ice it contains, and more massive giants turn out to hold more heavy elements in total but a smaller fraction of their mass [4].

### Eccentric orbits and neighbours

Warm Jupiters have more varied orbits than hot Jupiters. Many are eccentric, and about half of those found by Kepler have small planets orbiting close by, while hot Jupiters almost never do [5]. That difference is one of the strongest clues to how giants reach the inner parts of their systems (below).

The most extreme case is HD 80606 b, whose orbit is so elongated (eccentricity 0.93) that its distance from its star changes by a factor of about 30 over its 111-day year. The Spitzer Space Telescope watched its atmosphere heat rapidly as it swung past the star [6]; for most of its orbit it is a temperate giant and for a few days it is a hot Jupiter.

## Formation and migration

Radial-velocity surveys found fewer giants with periods of about 3 to 10 days than with shorter or longer periods, a gap between hot and warm Jupiters called the period valley [7]. Warm Jupiters are thought to reach their orbits in more than one way. Those with close, low-mass neighbours and circular orbits probably formed where they are, or migrated gently through the gas disc, since a violent history would have scattered their companions. Eccentric warm Jupiters may be hot Jupiters caught partway through high-eccentricity migration, in which a giant is flung onto an elongated orbit by another body and has its orbit slowly shrunk and circularised by tides raised at each close pass [5] [8].

## How we know

Warm Jupiters are found by radial-velocity surveys and, less often, by transits: a planet with a 100-day orbit is less likely to be aligned to transit and transits less often than one with a 3-day orbit. Their atmospheres are just starting to be measured. JWST detected methane throughout the atmosphere of WASP-80 b, an 825 K giant at the hot edge of this range, the gas the models expect to carry most of a temperate giant's carbon [9]. Direct imaging reaches the same temperatures by another route: young giants still warm from formation reach the same temperatures by their own heat: GJ 504 b, at about 510 K, has colours that suggest a largely cloud-free atmosphere [10], and 51 Eridani b, at 600 to 750 K, shows strong methane and water absorption [11]. One of the coldest giants imaged, epsilon Indi Ab at about 275 K, sits where water clouds might form, though it is warmed from inside rather than by its star [12]. No temperate giant has yet had its reflected colour measured, so the white and blue worlds remain predictions.

A temperate giant at the right distance from its star could also host large moons in its star's habitable zone, whose habitability would depend on the planet's shadow, reflected light and tidal heating as well as on the star [13].

## Notable examples

| Planet          | Notes                                                                                                           |
| --------------- | --------------------------------------------------------------------------------------------------------------- |
| HD 80606 b      | Eccentricity 0.93, 111-day orbit; its atmosphere heats rapidly at each close pass [6]                          |
| WASP-80 b       | 825 K; methane detected by JWST in both transmission and emission [9]                                          |
| GJ 504 b        | Young giant imaged directly; about 510 K and about 4 Jupiter masses, with colours that suggest few clouds [10] |
| 51 Eridani b    | Young giant imaged directly; 600 to 750 K, strong methane and water absorption [11]                            |
| epsilon Indi Ab | About 275 K from internal heat; one of the coldest giants imaged, and a candidate for water clouds [12]        |

> **In Pax Abyssi**
>
> **IN THE GAME.** Temperate gas giants (GGT) are giants whose equilibrium temperature is 150 to 700 K. The physics engine computes temperature and photochemical haze first and assigns the subtype from them, growing the haze with the star's ultraviolet output and the planet's metallicity. Because haze builds up easily in the warm, methane-rich range, most giants above 350 K end up Hazy, and the vivid Clear-Blue worlds are rare finds. Most temperate giants are placed by the warm-Jupiter system architecture. There are 260 among the 8,742 planets of the 5,159 generated systems: 149 Transition, 73 Hazy, 30 Clear-Blue and 2 Water-Cloud.
>
> Our gas giant generator has 16 temperate looks across the eight types. The Clear-Blue and Brilliant White giants show the physics most plainly: the jets and storms are still modelled beneath them, but with no cloud high enough to trace the flow, the disc stays smooth, as the models predict.

## See also

- [Sudarsky classification](https://paxabyssi.com/wiki/Sudarsky_classification.md)
- [Gas giant](https://paxabyssi.com/wiki/Gas_giant.md)
- [Cold gas giant](https://paxabyssi.com/wiki/Cold_gas_giant.md)
- [Hot Jupiter](https://paxabyssi.com/wiki/Hot_Jupiter.md)
- [Habitable zone](https://paxabyssi.com/wiki/Habitable_zone.md)
- [Moons](https://paxabyssi.com/wiki/Moons.md)

## References

1. Sudarsky, D., Burrows, A. and Pinto, P. (2000). Albedo and Reflection Spectra of Extrasolar Giant Planets. The Astrophysical Journal 538, 885-903. <https://doi.org/10.1086/309160>
2. Cahoy, K. L., Marley, M. S. and Fortney, J. J. (2010). Exoplanet Albedo Spectra and Colors as a Function of Planet Phase, Separation, and Metallicity. The Astrophysical Journal 724, 189-214. <https://doi.org/10.1088/0004-637X/724/1/189>
3. Demory, B. O. and Seager, S. (2011). Lack of Inflated Radii for Kepler Giant Planet Candidates Receiving Modest Stellar Irradiation. The Astrophysical Journal Supplement Series 197, 12. <https://doi.org/10.1088/0067-0049/197/1/12>
4. Thorngren, D. P. et al. (2016). The Mass-Metallicity Relation for Giant Planets. The Astrophysical Journal 831, 64. <https://doi.org/10.3847/0004-637X/831/1/64>
5. Huang, C., Wu, Y. and Triaud, A. H. M. J. (2016). Warm Jupiters Are Less Lonely than Hot Jupiters: Close Neighbors. The Astrophysical Journal 825, 98. <https://doi.org/10.3847/0004-637X/825/2/98>
6. Laughlin, G. et al. (2009). Rapid heating of the atmosphere of an extrasolar planet. Nature 457, 562-564. <https://doi.org/10.1038/nature07649>
7. Udry, S., Mayor, M. and Santos, N. C. (2003). Statistical properties of exoplanets. I. The period distribution: Constraints for the migration scenario. Astronomy & Astrophysics 407, 369-376. <https://doi.org/10.1051/0004-6361:20030843>
8. Dawson, R. I. and Johnson, J. A. (2018). Origins of Hot Jupiters. Annual Review of Astronomy and Astrophysics 56, 175-221. <https://doi.org/10.1146/annurev-astro-081817-051853>
9. Bell, T. J. et al. (2023). Methane throughout the atmosphere of the warm exoplanet WASP-80b. Nature 623, 709-712. <https://doi.org/10.1038/s41586-023-06687-0>
10. Kuzuhara, M. et al. (2013). Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-like Star GJ 504. The Astrophysical Journal 774, 11. <https://doi.org/10.1088/0004-637X/774/1/11>
11. Macintosh, B. et al. (2015). Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager. Science 350, 64-67. <https://doi.org/10.1126/science.aac5891>
12. Matthews, E. C. et al. (2024). A temperate super-Jupiter imaged with JWST in the mid-infrared. Nature 633, 789-792. <https://doi.org/10.1038/s41586-024-07837-8>
13. Heller, R. and Barnes, R. (2013). Exomoon Habitability Constrained by Illumination and Tidal Heating. Astrobiology 13, 18-46. <https://doi.org/10.1089/ast.2012.0859>

## Infobox (planet class)

| Field | Value |
| --- | --- |
| Code | GGT |
| Mass | about 0.1 to 13 M_Jup |
| Name | Temperate gas giant |
| Image | File:Pax_giant_GGT-WC-PB-2_phase70.webp |
| Level | Type |
| Radius | about 0.8 to 1.2; not inflated R_Jup |
| Series | G (gas giant) |
| Caption | In Pax Abyssi: a Pale Banded water-cloud giant (GGT-WC-PB) half lit by its star, white water-ice zones over pale blue belts |
| Subtypes | GGT-TN Transition (FD, EM), GGT-WC Water-Cloud (BW, PB), GGT-CB Clear-Blue (AZ, DP), GGT-HZ Hazy (SM, TN) |
| Sim source | Temperate gas giant physics engine and properties module; the temperate giant science reference; the procedural gas giant generator |
| Bond albedo | 0.10 to 0.81 (models) dimensionless |
| Legacy code | G3-T |
| Rings moons | Moons possible at the outer end; Hill spheres shrink closer in |
| Tidal state | Mostly not tidally locked; eccentric orbits common |
| Last verified | 2026-09-28 |
| Real examples | HD 80606 b (highly eccentric); WASP-80 b (825 K, methane, at the hot boundary); directly imaged GJ 504 b (about 510 K) and 51 Eridani b (600 to 750 K) have effective temperatures in this range |
| Typical orbit | About 0.1 to 1 AU around Sun-like stars (periods of weeks to about a year); closer around M dwarfs |
| Dominant gases | H2 and He; methane the main carbon carrier below about 800 K; water vapour; ammonia |
| Science status | observed (warm Jupiters' orbits, masses, radii, some spectra); model (clouds and colour); sim (subtypes) |
| Frequency in sim | 260 of the 8,742 planets in the 5,159 generated systems (TN 149, HZ 73, CB 30, WC 2) |
| Rendered example | All eight types in the specimen gallery below; 16 looks in the gas giant generator |
| Defining criteria | Pax Abyssi: equilibrium temperature 150 to 700 K. Subtypes by temperature and haze: Transition 150 to 250 K, Water-Cloud 250 to 350 K, Clear-Blue 350 K and above with haze optical depth below 0.05, Hazy the same with more haze |
| Interior structure | As for cold giants; radius not inflated, so radius and mass together reveal the heavy-element content |
| Literature equivalent | Warm Jupiter (orbital periods of roughly 10 to 200 days); Sudarsky classes II and III |
| Cloud and haze species | NH3 fading at the cool end; H2O ice clouds near 250 to 350 K; none in the upper atmosphere above about 350 K except photochemical haze |
| Equilibrium temperature | 150 to 700 K |

## Related pages

- [Hot Jupiter](https://paxabyssi.com/wiki/Hot_Jupiter.md): A gas giant orbiting so close to its star that its year lasts days and its dayside is hotter than lava. Hot Jupiters were the first planets found around Sun-like stars and remain the best-studied exoplanet atmospheres, though fewer than one Sun-like star in a hundred has one.
- [Cold gas giant](https://paxabyssi.com/wiki/Cold_gas_giant.md): A gas giant far enough from its star that ammonia freezes into clouds high in its atmosphere, like Jupiter and Saturn. Pax Abyssi sorts its cold giants into four subtypes by trace chemistry and ten types by weather, from calm pinstriped Jupiters to rust-hazed and snow-white worlds.
- [Gas giant](https://paxabyssi.com/wiki/Gas_giant.md): A planet made mostly of hydrogen and helium, with no solid surface, from about a tenth of Jupiter's mass up to the brown dwarf boundary near 13 Jupiter masses. Pax Abyssi sorts every giant it generates into five families and 41 types, by temperature, then chemistry, then weather, and draws each one from its physics.
- [Sudarsky classification](https://paxabyssi.com/wiki/Sudarsky_classification.md): A theoretical scheme from 2000 that sorts giant planets into five classes by the temperature of their upper atmospheres, which decides what clouds can form and so how much light, and what colour, the planet reflects.
- [Ice giant](https://paxabyssi.com/wiki/Ice_giant.md): A giant planet made mostly of water, methane and ammonia rather than hydrogen and helium, like Uranus and Neptune. Their interiors are hot, dense fluids, their magnetic fields are lopsided, and planets of about their mass may be among the commonest in the Galaxy. Pax Abyssi draws sixteen types of ice giant, from Neptune-blue storm worlds to hot, near-black ones.
- [Barren rock world](https://paxabyssi.com/wiki/Barren_rock_world.md): A rocky planet with no real atmosphere, whose surface lies bare to starlight, cosmic rays and meteorites. Mercury is the Solar System's example, and JWST has found several around other stars.

Categories: [Gas giants](https://paxabyssi.com/wiki/Category:Gas_giants.md), [Planet classes](https://paxabyssi.com/wiki/Category:Planet_classes.md), [Giant planets](https://paxabyssi.com/wiki/Category:Giant_planets.md)
