Superman: The Movie presented a far darker image of Krypton as compared to the comics of the time (1978). Whereas in the comics, Krypton was colorful, bright and idyllic, Superman: The Movie presented a planet with foreboding terrain of stark white with jagged frozen plateaus and dark skies.

krypton kryptonopolis

Kryptonians were portrayed as being a coolly cerebral society, clad in stark white, and treading halls under crystalline arches. The crystalline motif was employed not only in the architecture, but in the landscape and technology as well, suggesting that the entire planet had been adapted and altered by Kryptonian influence. Krypton itself was ultimately destroyed when its star began to collapse; the planet was pulled into the sun and ripped apart, then incinerated when the star went nova.

krypton_2 krypton_3
The death of Krypton

The film version of Krypton was presented as having a society "better" than Earth's. For instance, there was no death penalty because almost all criminals were rehabilitated (the ones that were not or were beyond rehabilitation such as General Zod were banished to the Phantom Zone). Kal-El thought very highly of the planet and was proud to have come from there. Also both Jor-El and Lara are able to preserve some part of their essence in the starship that brought their child to Earth, so that shortly after Clark Kent's eighteenth birthday, Jor-El appears to him within the Fortress of Solitude and initiates twelve years of Kryptonian education for the youth, and both remain as constructs within the Fortress until it is ransacked by Lex Luthor (in Superman Returns).

Superman's symbol is given a Kryptonian origin. Male Kryptonians are shown wearing unique symbols on the chests of their robes, similar to a family crest; Jor-El and Kal-El both wear the familiar S-shield.


However, for all their 'enlightened' ways, the governance of Krypton appeared to be by a committee made up of elders who were both short-sighted and over-bearing. When Jor-El attempted to argue his case on Krypton's impending doom he was warned not to tell anyone and when their surveillance equipment detected unauthorized energy use in Jor-El's laboratory, a security detachment was sent to arrest him.

Council Chambers
Jor-El's lab


What the real world tells us about Krypton's sun: Red stars come in two basic sizes - dwarves and giants. And red stars have a relatively cool surface. Another thing the real world tells us: The length of a planet's year is dependent on how far it is from its sun and the distance it needs to be from its sun is dependent on its size and luminosity.

Red Giant

Example: Scheat
Spectral Class: M2III
Diameter (Sol = 1): 95 R
Total Luminosity (Sol = 1): 1,500 L

Habitable zone: 37-40 AU
Length of Year: 38.7 Earth years
Angular size of sun from planet: 1.79°
[Sun has an angular size of 0.5° from Earth]

Red giant stars are not good candidates for having planets with native life - the star's life is too short.

Red Main Sequence

Spectral Class: M0
Diameter (Sol = 1): .64 R
Total Luminosity (Sol = 1): .075 L

Habitable zone: 0.24-0.29 AU
Length of Year: 76+ days
Angular size of sun from planet: 1.25°

Red main sequence stars are still very small and dim.

Red Dwarf

Example: Lacaille 9352
Spectral Class: M0.5V
Diameter (Sol = 1): 0.47-0.57 M
Total Luminosity (Sol = 1): 0.011 L

Habitable zone: .09-.11 AU
Length of Year: 18 days
Angular size of sun from planet: 2.39°

Red dwarf stars are not good candidates for having habitable planets. The habitable zone is extremely close to the star which would cause the planet to be 'tidal-locked' (like Mercury and the Moon with one side always facing the primary). Also, red dwarfs are almost always variable stars - their luminosity varies greatly over time.

Light on the surface of the planet would resemble that of an incandescent bulb - when visiting or living on such a planet, the eye would compensate, making the surface appear brighter and and 'whiter' than the star's light would otherwise suggest.

The comics gave Krypton a planetary system: Krypton was one of seven planets orbiting the star Rao. At the time of its destruction, Krypton had two moons: Koron and Mithen. The moon Xenon was spun out of its orbit and lost, while the inhabited moon of Wegthorn was destroyed by the scientist Jax-Ur. Remnants of this moon undoubtedly created a ring of debris orbiting the planet.


Diameter: 1095 km.
Mass (assuming a density similar to the Moon)[Moon = 1]: 0.20
Orbital period: 23.43 Earth days.
Semimajor Axis: 345869 km.
Angular size of moon from planet: .168°


Diameter: 1017 km.
Mass (assuming a density similar to the Moon)[Moon = 1]: 0.25
Orbital period: 27.44 Earth days.
Semimajor Axis: 384299 km.
Angular size of moon from planet: .163°

Other notes: Superman is described as having a greater that human-normal molecular density. However, this density cannot be much greater than Earth-normal otherwise someone would have noticed early on that Clark Kent, even as a child, weighed far more than he should have. This would indicate that the surface gravity on Krypton was not too dissimilar to Earth's. Certainly the gravity of Krypton would be well within human capacity to tolerate.

Giving Krypton a surface gravity of 20% higher than Earth and a density 20% greater than Earth's (traditionally Krypton's core, instead of being iron/nickel was of heavier metals) gives Krypton a mean radius almost identical to Earth's.

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