Difference between revisions of "Kerbol"

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m (It has been shown, even in the very images of the article, that this is not true.)
(Added back the infobox; if the sun has different properties in KSP2, then we may want to split the page.)
 
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{{:Kerbol/Data}}
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{{Infobox/Body}}
  
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[[Kerbol]] (officially called '''the Sun''', and also known as '''the Star''') is the star at the center of the '''[[Kerbol System]]'''. It is known to be orbited by five planets: '''[[Moho]]''', '''[[Eve]]''', '''[[Kerbin]]''', '''[[Duna]]''' and '''[[Jool]]''' and two dwarf planets '''[[Eeloo]]''' and '''[[Dres]]'''.
+
'''Kerbol''', A.K.A. the Sun, is the parent star of the '''[[Kerbol System]]''', making it the core of the explorable [[w:Planetary system|planetary system]] in [[KSP1]], as well as the first explorable planetary system in [[KSP2]]. Five planets: '''[[Moho]]''', '''[[Eve]]''', '''[[Kerbin]]''', '''[[Duna]]''' and '''[[Jool]]'''; and two dwarf planets: '''[[Dres]]''' and '''[[Eeloo]]'''; orbit around it. Kerbol contains 99.97% of the mass in the Kerbol system. This is very similar to our sun which contains 99.86% of the mass in the real world solar system.
  
−
Compared to our own [[w:Sun|Sun]], Kerbol is 113 times less massive and has a radius 3 times smaller. Kerbol is likely a [[w:K-type_main-sequence_star|K Class main sequence star]] based on it's temperature, but it may also be an [[w:Red_dwarf|M class star]] based on it's radius, or a [[w:G-type_main-sequence_star|G class star]] based on it's luminosity. However, based on it's mass, it would be a [[w:Sub-brown_dwarf|sub-brown dwarf]].
+
"Kerbol" was originally a fan-made portmanteau of "Kerbal" and "Sol" — the Latin name for the real-life [[w:Sun|Sun]]. Before {{version|0.11}} of KSP1, which introduced an object for Kerbin's parent star and an orbital [[Map view]] where it was explicitly named, it was an unnamed directional light source at infinite distance. Fans on the KSP forums invented and popularized the name, and the term "Kerbol System" was used in the official 1.2 release post, the first issue of "The Kerbal Chronicles" as well as in the official trailer for the KSP Enhanced Edition. Doing an ice chunk analysis on Eeloo can confirm this name in KSP1. In KSP2, the star is explicitly named "Kerbol".
  
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Orbiting just above the surface gives an orbital period of 409.214 Minutes and a speed of 66.945 km/s.
+
== In-game description ==
 +
{{Quote
 +
|The Sun is the most well known object in the daytime sky. Scientists have noted a particular burning sensation and potential loss of vision if it is stared at for long periods of time. This is especially important to keep in mind considering the effect shiny objects have on the average Kerbal.
 +
|[[Kerbal Astronomical Society]]}}
  
−
== Reference Frames ==
+
== Gravitational influence ==
 +
Escaping the SOI of any other body will place an object in orbit around the Sun (Kerbol). This will give a [[Science]] situation of being in space high over the Sun (Kerbol) until an altitude less than 1,000 Mm is reached. Low orbit can be reached by using a standard [[Tutorial: Advanced Orbiting#Hohmann transfer|Hohmann transfer]] from [[Kerbin]]'s orbit, this requires about 8 km/s of change-in-velocity (Δv). The more efficient way to reach low Sun (Kerbol) orbit, at the expense of drastically increased flight time, is to use a [[Tutorial: Advanced Orbiting#Bi-elliptical transfer|bi-elliptical transfer]]. With a sufficiently-distant apoapsis, the required Δv to "sundive" from Kerbin orbit can be reduced to under 4 km/s.
 +
 
 +
Previously the closest sustained altitude was 1,340 m, but now bodies emit radiation which heats parts and overheats parts before it could reach the atmosphere. The heating varies on the surface area it shines and part specific heat. Using parts with higher maximum temperature reduces the chance of [[overheating]], making the inflatable heat shield a good choice to shield your delicate parts from heat. This imposes a challenge where the objective is to get as close to the Sun as possible while surviving.
 +
 
 +
The [[sphere of influence]] (SOI) of the Sun (Kerbol) is infinite, making the Sun (Kerbol) inescapable. Thus, achieving gravitation-free flight is impossible. With a powerful enough ship, it is possible to get to the point where the info tab will display the craft's situation as "escaping" the Sun (Kerbol). The end of the patched conics path plotted by the game can be reached, at which point the spacecraft begins drawing a course behind it. But the actual escape never occurs. Presumably, this state would continue indefinitely, as the time required to find out what would happen would take several years real-time even at maximum time acceleration.
 +
 
 +
=== Landing ===
 +
Similar to [[Jool]], it's impossible to land on the Sun. Any objects are destroyed at an altitude below -250 m, which shows in the end flight dialog as "crashed into the surface of the sun" or similar, rather than ever landing.
 +
 
 +
One can attempt to place edited parts on the surface, but they bounce erratically at a few hundred to a few thousand meters per second if they do not explode.
 +
 
 +
== Temperature and luminosity ==
 +
[[File:Kerbol_temperature.png|thumbnail|left|Temperature-height profile of Kerbol's atmosphere.]]
 +
The Sun's (Kerbol's) visible surface, its [[w:Photosphere|photosphere]], has a temperature of 5840 K. This temperature, along with the star's yellow color, suggests that the Sun (Kerbol) is a [[w:G-type_main-sequence_star|Class G main-sequence star]]. Above the photosphere is a thin and hot atmosphere that is analogous to a [[w:Chromosphere|chromosphere]]. The chromosphere extends to a height of 600 km and has at its base a pressure of 16 kPa. The temperature of the chromosphere decreases with increasing altitude until reaching a minimum of 4000 K at a height of 50 km. Above 50 km the temperature increases with increasing altitude. The maximum temperature of 10,000 K is reached at the atmosphere's extreme upper limit.
 +
 
 +
Based on its given size and temperature, the Sun's (Kerbol’s) luminosity would be 56.7 yottawatts, however this is contradicted by other in-game physical parameters. The value of the solar constant at Kerbin is 1360 W/m<sup>2</sup>, which implies a solar luminosity of 3.16 yottawatts (0.008 Solar luminosities) and a surface temperature of 2840&nbsp;K. These values are consistent with a [[w:Red dwarf|Class M red dwarf]].
 +
 
 +
== Physical appearance ==
 +
The equatorial radius of the Sun is almost four times than that of Jupiter and 43.6 times larger than Jool's, the largest planet known in the Solar (Kerbol) system. <!-- Jupiter's radius is about 67 000&nbsp;km, the Sun's (Kerbol's) radius is about 3.8 times greater --> the Sun (Kerbol) has the yellow color of a [[w:G-type_main-sequence_star|Class G main-sequence star]] and its [[w:Absolute_magnitude|absolute bolometric magnitude]] is approximately +10. If close enough, one can see that the [[w:Sunspot|dark spots]] are indented.
 +
 
 +
The "corona" surrounding the Sun (Kerbol) is not the actual size of the sun as it appears. It will shrink and grow relative to the location of the viewpoint, just as the size of Kerbol does normally. However, it won't shrink past a certain point, and if the sun is viewed from a far enough point, the corona is still very visible. This is apparent when using camera or telescope [[mods]] that remove the corona and show the Sun's (Kerbol's) true size, which is usually much smaller than the corona appears.
 +
 
 +
=== Past appearances ===
 +
[[File:Kerbol.jpg|thumbnail|left|Prior to {{version|0.11}} there was only a nameless light in space.]]
 +
{{Version|0.7.3}} introduced the parent star of Kerbin as a slightly red-tinted directional light (with lots of lens flare) in the skybox at infinite distance, thus impossible to reach.
 +
[[File:KerbolSurface.png|thumbnail|Surface in {{version|0.17}}.]]
 +
In {{version|0.11}}, it became a yellow sphere which could be visited but its surface wasn't solid. It was named "The Sun" in Map view; however, fans had already taken to calling the star "Kerbol". Up to {{version|0.13.3}} dropping below the "surface" was still safe, but a ship could break up from the extreme gravity gradients and/or be shot outwards at large fractions of the speed of light.
 +
 
 +
== Reference frames ==
 
{{:Kerbol/RefFrame}}
 
{{:Kerbol/RefFrame}}
−
All Kerbol orbits are in an inertial reference frame. In the old demo, getting close enough to experience the lower maximum time warps results [[Deep Space Kraken]] attacks.
 
  
 
== Trivia ==
 
== Trivia ==
−
* Between versions 0.7 and 0.10.1, Kerbol was a mere point of light in the skybox.
+
* The Sun has just under twice the surface gravity of Kerbin, thus only slightly more than Eve's.
−
* Kerbol gained gravity in 0.12.
+
* The Kerbal Sun is not a realistic analogue of our Real Sun.
−
* It is still safe to drop below the 'surface' in 0.13.3, but a ship can break up from the extreme gravity gradients and/or shot outwards at large fractions of c.
+
** The Mun is larger and closer to Kerbin than Moon to Earth, and thus in order to make eclipses work right, the Sun was made large enough to fit.
−
* Since 0.14, the “surface” of Kerbol is an invisible, and nearly featureless plateau approximately 4500-4700 km above the nominal radius. There is no known way to land on it, as the [[Kraken]] makes all maneuvering difficult, and the gravity reduces the TWR of all engines below 1. One can attempt to place edited parts on the surface, but they bounce erratically at a few hundred to a few thousand m/s if they do not explode.
+
 
−
* While Kerbol can be reached from [[Kerbin]]'s orbit by using a [[Mun Landing#Step 2 - To The Mun|Hohmann transfer orbit]], a spacecraft doing so will require a Δv of about 8 km/s to do so. The most efficient way to reach Kerbol from Kerbin orbit is to use a [[Tutorial:_Advanced_Orbiting#Bi-Elliptical_Transfer|bi-elliptic transfer]]. With a sufficiently-distant apoapsis, the required ΔV to sundive can be reduced to under 4 km/s, at the expense of drastically-increased flight time.
+
=== Real-world comparison ===
−
* The name “Kerbol” was created by forum members and never appears in the game. Officially, the star is simply referred to as “the Sun”, though the lead developer did mention that the name could change once the need to differentiate it from other stars arises.
+
While otherwise analogous to our own real-life [[w:Sun|Sun]], the Sun (Kerbol) has 1/113<sup>th</sup> the mass and 1/3<sup>rd</sup> its radius. The Sun's (Kerbol's) other attributes can be used to derive the following statistics: it has a luminosity of approximately 3 yottawatts based on the solar constant at Kerbin; a defined surface temperature of 5840 K (that of a [[w:Stellar_classification#Class_G|Class G star]]), but a temperature less than 3000&nbsp;K based on its size and luminosity (that of a [[w:Stellar_classification#Class_M|Class M star]]); the radius of a [[w:Red dwarf|red dwarf]]; and the mass of a [[w:Sub-brown dwarf|sub-brown dwarf]]. Such a star in real life would be on the limits of Hydrostatic equilibrium and its small size would mean it would only generate as much heat as a red dwarf. However, many astrophysical properties in KSP are effectively scaled down for gameplay.
−
* Kerbol's Sphere of Influence is infinite, which makes it impossible to escape its orbit and achieve gravitation-free flight.
+
 
−
* Once your Kerbol apoapsis reaches a certain point, it will always say it takes 68 years to reach. This is because times in Kerbal Space Program are limited to 2<sup>32</sup>-1 seconds as a consequence of how numbers are handled.
+
Its real-life counterpart according to its size and mass would be [https://en.wikipedia.org/wiki/2MASS_J0523-1403 2MASS J0523-1403], the smallest star currently known.
−
* Kerbol has just under twice the surface gravity of Kerbin not to mention, Eve has a merely 0.4 m/s² lower of surface gravity than Kerbol.
 
−
* Kerbol's heat will always destroy a craft, even with the "No crash damage" cheat enabled. This makes landing on Kerbol impossible.
 
−
* There are long-term plans for solar flares and prominences, making a low Kerbol orbit even more dangerous.{{cn}} <!-- is this speculation, or an actual plan of the devs? -->
 
−
* Kerbol's equatorial radius is roughly three times that that of Jupiter.
 
  
 
== Gallery ==
 
== Gallery ==
 +
=== [[Kerbal Space Program]] ===
 
<gallery>
 
<gallery>
 
KerbolSurface.png | A picture taken of a probe on a close encounter with Kerbol shortly before overheating.
 
KerbolSurface.png | A picture taken of a probe on a close encounter with Kerbol shortly before overheating.
−
Kerbol17.png     | Up close it becomes evident that the glow is [[w:Nonagon|ennagonal]].
+
Kerbol17.png | Up close the lens flare becomes evidently [[w:Nonagon|ennagonal]].
−
Isa_kerbol.gif    | ISA MapSat output for Kerbol Star (this is a pre-made "map" that comes with the plugin and is not based on any measured terrain data)
+
Kerbolterrain.png | Elevation shown on Kerbol
−
Kerbolterrain.png   | Elevation shown on Kerbol
+
Close approach to Sun.png | A close flyby of Kerbol
 
</gallery>
 
</gallery>
  
 
== Changes ==
 
== Changes ==
−
 
+
=== [[Kerbal Space Program]] ===
−
;{{Version|0.18.2|}}
+
;[[1.3]]
 +
* Changed displayName to The Sun, removed useTheInName = true feature.
 +
;[[1.0]]
 +
* Added an atmosphere.
 +
;[[0.18.2]]
 
* Art pass.
 
* Art pass.
−
;{{Version|0.17|}}
+
;[[0.17]]
 
* Actual model added, new sprite/flare effect, size changed.
 
* Actual model added, new sprite/flare effect, size changed.
−
;{{Version|0.14|}}
+
;[[0.14]]
−
* Added solid surface (featureless invisible plateau ~4500-4700 km above nominal radius).
+
* Added solid surface (featureless invisible plateau ~4500–4700&nbsp;km above nominal radius).
−
;{{Version|0.12|}}
+
;[[0.12]]
−
* Added Gravity, nominal radius of 65,400 km.
+
* Added Gravity, nominal radius of 65,400&nbsp;km.
−
;{{Version|0.11|}}
+
;[[0.11]]
−
* Made it possible to reach Kerbol.
+
* Made it possible to reach the Sun (Kerbol).
−
;{{Version|0.7.3|}}
+
;[[0.7.3]]
 
* Initial Release.
 
* Initial Release.
 +
 +
=== [[Kerbal Space Program 2]] ===
 +
;0.1.1
 +
* Fixed description for Kerbol capture and Kerbosationary orbit trip stages in trip planner.
 +
* Improved Kerbol flare/bloom effects.
 +
;0.1.0
 +
* Initial release.
  
 
{{Celestial Bodies}}
 
{{Celestial Bodies}}
 
[[Category:Celestials]]
 
[[Category:Celestials]]

Latest revision as of 01:50, 15 July 2023

Kerbol
Kerbol
Kerbol as seen from orbit.
Star
Physical Characteristics
Equatorial radius 261 600 000 m
Equatorial circumference 1 643 681 276 m
Surface area 8.5997404×1017 m2
Mass 1.7565459×1028 kg
Standard gravitational parameter 1.1723328×1018 m3/s2
Density 234.23818 kg/m3
Surface gravity 17.1 m/s2 (1.747 g)
Escape velocity 94 672.01 m/s
Sidereal rotation period 432 000.00 s
20 d 0 h 0 m 0 s
Sidereal rotational velocity 3 804.8 m/s
Synchronous orbit 1 508 045.29 km
Sphere of influence ∞
Atmospheric Characteristics
Atmosphere present Yes
Atmospheric pressure 16.0000 kPa
0.157908 atm
Atmospheric height 600 000 m
1.6×10-7 atm
Temperaturemin 3741.80 °C 4014.95 K
Temperaturemax 9348.05 °C 9621.2 K
Oxygen present No
Scientific multiplier
Surface N/A
Splashed N/A
Lower atmosphere 1
Upper atmosphere 1
Near space 11
Outer space 2
Recovery 4

Kerbol, A.K.A. the Sun, is the parent star of the Kerbol System, making it the core of the explorable planetary system in KSP1, as well as the first explorable planetary system in KSP2. Five planets: Moho, Eve, Kerbin, Duna and Jool; and two dwarf planets: Dres and Eeloo; orbit around it. Kerbol contains 99.97% of the mass in the Kerbol system. This is very similar to our sun which contains 99.86% of the mass in the real world solar system.

"Kerbol" was originally a fan-made portmanteau of "Kerbal" and "Sol" — the Latin name for the real-life Sun. Before version 0.11 of KSP1, which introduced an object for Kerbin's parent star and an orbital Map view where it was explicitly named, it was an unnamed directional light source at infinite distance. Fans on the KSP forums invented and popularized the name, and the term "Kerbol System" was used in the official 1.2 release post, the first issue of "The Kerbal Chronicles" as well as in the official trailer for the KSP Enhanced Edition. Doing an ice chunk analysis on Eeloo can confirm this name in KSP1. In KSP2, the star is explicitly named "Kerbol".

In-game description

“ The Sun is the most well known object in the daytime sky. Scientists have noted a particular burning sensation and potential loss of vision if it is stared at for long periods of time. This is especially important to keep in mind considering the effect shiny objects have on the average Kerbal.

— Kerbal Astronomical Society

 ”

Gravitational influence

Escaping the SOI of any other body will place an object in orbit around the Sun (Kerbol). This will give a Science situation of being in space high over the Sun (Kerbol) until an altitude less than 1,000 Mm is reached. Low orbit can be reached by using a standard Hohmann transfer from Kerbin's orbit, this requires about 8 km/s of change-in-velocity (Δv). The more efficient way to reach low Sun (Kerbol) orbit, at the expense of drastically increased flight time, is to use a bi-elliptical transfer. With a sufficiently-distant apoapsis, the required Δv to "sundive" from Kerbin orbit can be reduced to under 4 km/s.

Previously the closest sustained altitude was 1,340 m, but now bodies emit radiation which heats parts and overheats parts before it could reach the atmosphere. The heating varies on the surface area it shines and part specific heat. Using parts with higher maximum temperature reduces the chance of overheating, making the inflatable heat shield a good choice to shield your delicate parts from heat. This imposes a challenge where the objective is to get as close to the Sun as possible while surviving.

The sphere of influence (SOI) of the Sun (Kerbol) is infinite, making the Sun (Kerbol) inescapable. Thus, achieving gravitation-free flight is impossible. With a powerful enough ship, it is possible to get to the point where the info tab will display the craft's situation as "escaping" the Sun (Kerbol). The end of the patched conics path plotted by the game can be reached, at which point the spacecraft begins drawing a course behind it. But the actual escape never occurs. Presumably, this state would continue indefinitely, as the time required to find out what would happen would take several years real-time even at maximum time acceleration.

Landing

Similar to Jool, it's impossible to land on the Sun. Any objects are destroyed at an altitude below -250 m, which shows in the end flight dialog as "crashed into the surface of the sun" or similar, rather than ever landing.

One can attempt to place edited parts on the surface, but they bounce erratically at a few hundred to a few thousand meters per second if they do not explode.

Temperature and luminosity

Temperature-height profile of Kerbol's atmosphere.

The Sun's (Kerbol's) visible surface, its photosphere, has a temperature of 5840 K. This temperature, along with the star's yellow color, suggests that the Sun (Kerbol) is a Class G main-sequence star. Above the photosphere is a thin and hot atmosphere that is analogous to a chromosphere. The chromosphere extends to a height of 600 km and has at its base a pressure of 16 kPa. The temperature of the chromosphere decreases with increasing altitude until reaching a minimum of 4000 K at a height of 50 km. Above 50 km the temperature increases with increasing altitude. The maximum temperature of 10,000 K is reached at the atmosphere's extreme upper limit.

Based on its given size and temperature, the Sun's (Kerbol’s) luminosity would be 56.7 yottawatts, however this is contradicted by other in-game physical parameters. The value of the solar constant at Kerbin is 1360 W/m2, which implies a solar luminosity of 3.16 yottawatts (0.008 Solar luminosities) and a surface temperature of 2840 K. These values are consistent with a Class M red dwarf.

Physical appearance

The equatorial radius of the Sun is almost four times than that of Jupiter and 43.6 times larger than Jool's, the largest planet known in the Solar (Kerbol) system. the Sun (Kerbol) has the yellow color of a Class G main-sequence star and its absolute bolometric magnitude is approximately +10. If close enough, one can see that the dark spots are indented.

The "corona" surrounding the Sun (Kerbol) is not the actual size of the sun as it appears. It will shrink and grow relative to the location of the viewpoint, just as the size of Kerbol does normally. However, it won't shrink past a certain point, and if the sun is viewed from a far enough point, the corona is still very visible. This is apparent when using camera or telescope mods that remove the corona and show the Sun's (Kerbol's) true size, which is usually much smaller than the corona appears.

Past appearances

Prior to version 0.11 there was only a nameless light in space.

version 0.7.3 introduced the parent star of Kerbin as a slightly red-tinted directional light (with lots of lens flare) in the skybox at infinite distance, thus impossible to reach.

Surface in version 0.17.

In version 0.11, it became a yellow sphere which could be visited but its surface wasn't solid. It was named "The Sun" in Map view; however, fans had already taken to calling the star "Kerbol". Up to version 0.13.3 dropping below the "surface" was still safe, but a ship could break up from the extreme gravity gradients and/or be shot outwards at large fractions of the speed of light.

Reference frames

Time warp Minimum Altitude
1× Any
5× 3 270 000 m
10× 3 270 000 m
50× 6 540 000 m
100× 13 080 000 m
1 000× 26 160 000 m
10 000× 52 320 000 m
100 000× 65 400 000 m

Trivia

  • The Sun has just under twice the surface gravity of Kerbin, thus only slightly more than Eve's.
  • The Kerbal Sun is not a realistic analogue of our Real Sun.
    • The Mun is larger and closer to Kerbin than Moon to Earth, and thus in order to make eclipses work right, the Sun was made large enough to fit.

Real-world comparison

While otherwise analogous to our own real-life Sun, the Sun (Kerbol) has 1/113th the mass and 1/3rd its radius. The Sun's (Kerbol's) other attributes can be used to derive the following statistics: it has a luminosity of approximately 3 yottawatts based on the solar constant at Kerbin; a defined surface temperature of 5840 K (that of a Class G star), but a temperature less than 3000 K based on its size and luminosity (that of a Class M star); the radius of a red dwarf; and the mass of a sub-brown dwarf. Such a star in real life would be on the limits of Hydrostatic equilibrium and its small size would mean it would only generate as much heat as a red dwarf. However, many astrophysical properties in KSP are effectively scaled down for gameplay.

Its real-life counterpart according to its size and mass would be 2MASS J0523-1403, the smallest star currently known.

Gallery

Kerbal Space Program

  • A picture taken of a probe on a close encounter with Kerbol shortly before overheating.

  • Up close the lens flare becomes evidently ennagonal.

  • Elevation shown on Kerbol

  • A close flyby of Kerbol

Changes

Kerbal Space Program

1.3
  • Changed displayName to The Sun, removed useTheInName = true feature.
1.0
  • Added an atmosphere.
0.18.2
  • Art pass.
0.17
  • Actual model added, new sprite/flare effect, size changed.
0.14
  • Added solid surface (featureless invisible plateau ~4500–4700 km above nominal radius).
0.12
  • Added Gravity, nominal radius of 65,400 km.
0.11
  • Made it possible to reach the Sun (Kerbol).
0.7.3
  • Initial Release.

Kerbal Space Program 2

0.1.1
  • Fixed description for Kerbol capture and Kerbosationary orbit trip stages in trip planner.
  • Improved Kerbol flare/bloom effects.
0.1.0
  • Initial release.
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