Time

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Revision as of 00:11, 1 June 2013 by Sadron (talk | contribs) (Phase angles)
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Kerbin Calendar

The following table outlines the orbital period and frequency of each Celestial Body in the Kerbol system. The MET lists time based on an Earth Year - 365 days - the following table calculates Earth Months as 365/12 ≈ 30.4 days. A sidereal Kerbin day is 6 hours long, the Mun has an orbital period of 38.60 hours which defines a Kerbin Month, and Kerbin has an orbital period of 2556.50 hours which defines a Kerbin Year.

Celestial Body Parent Hours Kerbin Earth Revolutions
per Hour
Revolutions per Kerbin Revolutions per Earth
Days Months Years Days Months Years Day Month Year Day Month Year
Moho Kerbol 615.49 102.58 15.95 0.24 25.65 0.84 0.07 0.00 0.01 0.06 4.15 0.04 1.19 14.23
Eve Kerbol 1571.7 261.95 40.72 0.61 65.49 2.15 0.18 0.00 0.00 0.02 1.63 0.02 0.46 5.57
Gilly Eve 107.9 17.98 2.80 0.04 4.50 0.15 0.01 0.01 0.06 0.36 23.69 0.22 6.77 81.19
Kerbin Kerbol 2556.50 426.08 66.23 1.00 106.52 3.50 0.29 0.00 0.00 0.02 1.00 0.01 0.29 3.43
Mun Kerbin 38.60 6.43 1.00 0.02 1.61 0.05 0.00 0.03 0.16 1.00 66.23 0.62 18.91 226.94
Minmus Kerbin 299.50 49.92 7.76 0.12 12.48 0.41 0.03 0.00 0.02 0.13 8.54 0.08 2.44 29.25
Duna Kerbol 4809.80 801.63 124.61 1.88 200.41 6.59 0.55 0.00 0.00 0.01 0.53 0.00 0.15 1.82
Ike Duna 18.20 3.03 0.47 0.01 0.76 0.02 0.00 0.05 0.33 2.12 140.47 1.32 40.11 481.32
Dres Kerbol 13303.60 2217.27 344.65 5.20 554.32 18.22 1.52 0.00 0.00 0.00 0.19 0.00 0.05 0.66
Jool Kerbol 29072.60 4845.43 753.18 11.37 1211.36 39.83 3.32 0.00 0.00 0.00 0.09 0.00 0.03 0.30
Laythe Jool 14.70 2.45 0.38 0.01 0.61 0.02 0.00 0.07 0.41 2.63 173.91 1.63 49.66 595.92
Vall Jool 29.43 4.91 0.76 0.01 1.23 0.04 0.00 0.03 0.20 1.31 86.87 0.82 24.80 297.66
Tylo Jool 58.87 9.81 1.53 0.02 2.45 0.08 0.01 0.02 0.10 0.66 43.43 0.41 12.40 148.80
Bop Jool 110.92 18.49 2.87 0.04 4.62 0.15 0.01 0.01 0.05 0.35 23.05 0.22 6.58 78.98
Pol Jool 153.70 25.62 3.98 0.06 6.40 0.21 0.02 0.01 0.04 0.25 16.63 0.16 4.75 56.99
Eeloo Kerbol 43608.90 7268.15 1129.76 17.06 1817.04 59.74 4.98 0.00 0.00 0.00 0.06 0.00 0.02 0.20

Phase angles

These are the phase angles of other planets, relative to Kerbin and ahead of Kerbin in the direction of rotation (taken using MechJeb2) at the beginning of the game (Year 1 day 1 00:00:00).

Planet Degrees Revolutions
Moho 84.92° 0.23589
Eve 15.00° 0.04167
Duna 135.51° 0.37642
Jool 238.43° 0.66231
Dres 10.02° 0.02783
Eeloo 309.98° 0.86106

These starting angles will allow you to calculate what the phase angle will be at any given moment. And you don't need to use any tools such as MechJeb to tell an exact moment when the planets are aligned for a transfer orbit.

For example the revolutions per second (RPS) for Duna is a full rotation divided by Duna's orbital period (1 / 17315400s). Then you can get the same revolutions per seconds value for Kerbin exactly the same way. To get the phase angle change per second one simply subtracts Kerbin_RPS from the target planet RPS.

Duna_RPS - Kerbin_RPS = -5.09017e-08

Using Kosmo-not's instructions one can calculate that the optimal phase angle for Kerbin - Duna transfer orbit is 0.12323 revolutions. We simply divide the desired change in phase angle by the angular change per second to get time until next transfer window.

(Desired phase angle) - (Duna phase angle at game start) = Desired change in angle

(Desired change in angle) / -5.09017e-08 = 4974119

So the first transfer window to Duna will be 4974119 seconds after game start, and will repeat every 19645699 seconds (-1 / -5.09017e-08).