Kerbin Year to Earth Year

[RA3236]

Hi,

I'm trying to do my novel, but I came up into an issue: if the following times were the same, what would the Earth time if the Kerbin time was Year 20, Day 358, Hour 1, Minute 34?

Earth:

• 24.4.2402, 23:53 in DD.MM.YYYY format and 24-hour time

Kerbin

• Year 20, Day 357, Hour 2, Minute 21

Thanks, I can't figure out the maths to it and I would really appreciate this.

Also, if there was an equation I could use for myself could you show me?

Edited May 3, 2016 by RA3236

[Streetwind]

 

On 3.5.2016 at 9:25 AM, RA3236 said:

if the following times were the same, what would the Earth time if the Kerbin time was Year 20, Day 358, Hour 1, Minute 34?

A solar day on Earth is 24 hours long (with reasonable precision), and there are 365.25 solar days in an Earth year - generally expressed as three years of 365 days followed by a leap year of 366 days.

A solar day on Kerbin is exactly 6 hours long, and there are 426 solar days in a Kerbin year. (I am unsure if it hits the 426 exactly, or if there's such a thing as leap years for Kerbin.)

 

To compare dates, it's best to write them in the same format. 2402 is not a leap year, so the 24th of April is the 114th day of that year (31 + 28 + 31 + 24).

Earth: Year 2402, Day 114, Hour 23, Minute 53
Kerbin: Year 20, Day 357, Hour 2, Minute 21

In order to progress to Year 20, Day 358, Hour 1, Minute 34 on Kerbin, 4 hours and 73 minutes - or 5 hours and 13 minutes - of time needs to elapse.

Adding that amount of time to the Earth date, we get Year 2402, Day 115, Hour 5, Minute 6. In other words, the 25th of April 2402, just after 5 in the morning.

 

Hope that helps!

Edited May 4, 2016 by Streetwind

[kerbiloid]

In any case you should select an initial Earth year, some Earth year when you presume 01.01.YYYY on Earth = 01.01.0000 on Kerbin. And count days from that date.

According to wiki , "Kerbal Space Program first compiled on 2011 January 17". So, you can take 2011 as a Kerbals' Great Awakening Year and use "01.01.2011 00:00:00 GMT" as a zero moment "00.00.0001 0:00:00 KMT".

 

In the Kerbin system you use not a Kerbin's planetary time (counting visible passes of the Sun over the sky watching from surface), but some absolute time, and there is integer days amount in a year, so there cannot be a leap year.
If you were an ancient Kerbal gazing at the Sun from the ground and creating an empiric calendar, then you would get a fractional days number in a year and probably should use leap years with an additional day or month.

Edited May 4, 2016 by kerbiloid

[Streetwind]

49 minutes ago, kerbiloid said:

In the Kerbin system you use not a Kerbin's planetary time (counting visible passes of the Sun over the sky watching from surface)

Yes you do. One of the recent KSP updates (was it 1.0?) specifically changed Kerbin's rotation so that a solar day is exactly 6 hours, and the same timescale is used by default for the mission elapsed timer as well as the time-from-epoch counter in the space center.

As a result of this change, the sidereal rotation period is now slightly shorter, meaning that a geostationary satellite will need an orbital period of some 5 hours 59 minutes 9.4 seconds. But since solar days is what you actually use for timekeeping (much like we do here on Earth), everything becomes much easier in that respect - including converting time into Earth date format.

But I just looked up Kerbin's data on the wiki, and it turns out that its orbital period is 426 days, 32 minutes and 24.6 seconds. In other words, Kerbin experiences a leap year every 11.10 years. This is rather unfortunate, as the deviation from a clean 11-year rhythm is significant. Earth, too, has a deviation from its 4-year rhythm, but it's much smaller than that and therefore doesn't really come into play for our calendars. On Kerbin though, every tenth leap year would be a "double leap" which must be two days longer, not one day longer.

Thus the ingame years 11, 22, 33 and so on would actually have to have 427 days, while the years 110, 220, 330 and so on would be 428 days. This isn't reflected in the game's timekeeping though, IIRC, which always counts fixed 426-day years. I would try to confirm this, but I don't have access to KSP at the moment.

@RA3236 - now you have to ask yourself if you want to count leap years for both planets, count them only for Earth, or count neither. Only the first case is strictly correct, but depending of the way the ingame date is displayed, might become complicated since you potentially have to manually account for Kerbin's two-staged leap year adjustments.

Edited May 4, 2016 by Streetwind

[RA3236]

@Streetwind I know about the leap years not being counted.

Thanks all for the input, I'll keep all of these in mind. The sol day is not a bad idea either.