Time
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).
