Otho as seen from orbit.
[[Otho/Param|Otho/Param]] of [[Otho/Param]]
Orbital Characteristics
Semi-major axis  m [Note 1]
Apoapsis  m [Note 1]
Periapsis  m [Note 1]
Orbital eccentricity Expression error: Unrecognised punctuation character "[".
Orbital inclination Expression error: Unrecognised punctuation character "[". °
Argument of periapsis Otho/Param °
Longitude of the ascending node Otho/Param °
Mean anomaly Expression error: Unrecognised punctuation character "[". rad (at 0s UT)
Sidereal orbital period  s
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Synodic orbital period Expression error: Unexpected < operator. s
Orbital Velocity to  m/s
Physical Characteristics
Equatorial radius  m
Equatorial Circumference  m
Surface area Expression error: Unexpected < operator. m2
Mass Expression error: Unexpected < operator. kg
Standard gravitational parameter Expression error: Unexpected < operator. m3/s2
Density Expression error: Unexpected < operator. kg/m3
Surface gravity Expression error: Unexpected < operator. m/s2 (Expression error: Unrecognised punctuation character "[". g)
Escape velocity  m/s
Sidereal rotation period Expression error: Unrecognised punctuation character "[". s
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Sidereal rotational velocity Expression error: Unexpected < operator. m/s
Synchronous orbit  km
Sphere of influence Expression error: Unexpected < operator. m [Note 1]
Atmospheric Characteristics
Atmosphere present Expression error: Unrecognised punctuation character "[".

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Scientific multiplier
Surface Otho/Param
Splashed Otho/Param

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Near space Otho/Param
Outer space Otho/Param
Recovery Otho/Param

  1. 1.0 1.1 1.2 1.3 The distances are given from the bodies center not surface (unlike ingame)

Otho is the 7th planet in the Ciro system and a member of the Galilean planets. It is the innermost and second largest of the three gas giant planets that dominate the outer solar system. Otho has three moons – Augustus, Hephaestus, and Jannah.

Otho effectively stands in for the stock planet Jool. It is worth noting that none of the Galilean gas giants meet Jool's mass or its radius of 6,000km but they all do surpass it in density and, therefore, still have higher surface gravity. With roughly half the influence radius there isn't much room for a full complement of 5 moons. Otho's apoapsis and periapsis differ from Jool's by only roughly 4 million km or 4Gm.

In-game description

"The first of the gas giants is a very mellow and very yellow entity. The sight of him and his fellow yellow moons is breathtaking. Even the rowdiest individual quiets down when they catch Otho staring back at them."
- Deep Sky Press

Physical Characteristics

Otho is the second largest planet, having approximately twice the mass of Gauss and half the mass of Nero. In comparison to Gael, it has about six times the radius and 31 times the mass. If scaled up to life-sized proportions, Otho would have about 1.4 times the radius and 1.6 times the mass of the planet Neptune.


Otho’s atmosphere consists predominately of hydrogen (84%), with some helium (5%) and other gases. The datum that defines Otho’s “surface” is the altitude at which the atmospheric pressure is 15 atmospheres.

The top of Otho’s atmosphere lies 600 km above the datum. Here the temperature averages -90°C. Descending through the atmosphere, the temperature decreases while the pressure rises exponentially. The temperature reaches a minimum of about -166°C at the 0.1 atm level (231 km altitude). Below this level the temperature steadily increases due to internal heat generated from gravitational contraction. At the 1 atm level (148 km) the temperature is -142°C. The temperature rises to -36°C (237 K) at the datum.

It is presumed that as one descends below the datum, the atmospheric pressure and temperature continues to rise, eventually reaching thousands of atmospheres and thousands of degrees. This region is impossible to explore, however, because all craft are hardcoded to implode the instant they reach an altitude of -250 meters.

Otho’s upper atmosphere experiences some latitudinal, diurnal, and seasonal temperature variations. These variations are greatest at the upper boundary, where temperature can range by as much as 22°C. The magnitude of the temperature variations decrease with decreasing altitude, with no global variation at altitudes below the 1 atm level.

Flight Performance

To be added.


Otho has 5 natural biomes:

  • Judgement
  • Hazy Halo
  • Eclipsing Veil
  • Hallowed Eddies
  • Temperate Tempests

Gameplay Features

  • Otho’s cloud bands have differential rotation, made possible by the optional plugin Stock Visual Enhancements. With this installed and some generous time warp the animation becomes very clear.
  • Any craft that descends to an altitude of -250 meters instantly implodes.
  • Unlike the other giants or most other Galilean planets in general, Otho is quite generous with his Karbonite concentration.


  • In real life, the 1 bar (≈1 atm) pressure level is usually used to define the datum for gas planets.
  • By sheer coincidence in early development, Otho, Augustus and Hephaestus all turned out to be hues of yellow and orange. This was later subtly applied to Jannah, completing the set and theme "Otho and his fellow yellow moons"


Otho has two associated flags. The first of which is its region flag, The Oth and their Hallowed Space, and the second is the Three Kings challenge flag, by which any vessel that wears it is bound exclusively to visit all of the gas planets and all of their moons. Entering other SOI except Gael's is prohibited.