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I think it's unlikely. Colloquially a year is 365 days. But if you actually watch Earth complete an orbit in space, it will not be at the same rotation around its axis at the end as when it starte...
Answer
#2: Post edited
by
matthewsnyder
·
2023-06-22T07:09:12Z (11 months ago)
- I think it's unlikely.
- Colloquially a year is 365 days. But if you actually watch Earth complete an orbit in space, it will not be at the same rotation around its axis at the end as when it started. It actually takes about 365.25 rotations to complete an orbit. This leads to the leap year.
- The side of the Earth closer to the Sun gets pulled in more than the far side. Because it's constantly rotating, there is a slight, continuous "reshaping" of the Earth by solar gravity. As the insides of Earth move around they experience friction, which bleeds off rotational energy and makes the day get longer and longer over time. So, many years in the future, the length of a day should increase from 1/365.25 years to 1/365 years exactly. An increase of only 0.07%! At that point, you would not need leap years. The problem is that it will not stop there, but keep increasing and then introduce a leap year again. Although, again the process is quite slow, so you can easily have it last entire *anthropic* time periods (thousands of years).
- However, it's also a question of how precise your people are, really. If a year is 365.0001 days, will bother adding a leap year once every millenium? Or will they simply disregard it? As you get more precise with this, the period it lasts for becomes briefer.
- In any case, it would be a bit much to expect *all* the planets in a system to coincide at whole-multiple years. Some of them would surely be fractional even while the others are not. So once your people develop astronomy, they are likely to become disappointed regardless... Unless they place some special importance on their one, precise, home planet.
- Synchronizing lunar and solar calendars is very unlikely, I think. You could always claim it is coincidental, but that's a heck of a coincidence. There might be some tidal effects from the Sun as the two planets are orbiting each other, but these would be much weaker than the one synchronizing the day to the solar year, which is already weak unless the planet is close enough to be scorched like Mercury.
There is also no reason why the lunar calendar would sync up with the solar *at the same time* as the solar year becoming an integral multiple of the day. These two things are not strongly related, and them co-occurring is even more unlikely than one happening on its own.
- I think it's unlikely.
- Colloquially a year is 365 days. But if you actually watch Earth complete an orbit in space, it will not be at the same rotation around its axis at the end as when it started. It actually takes about 365.25 rotations to complete an orbit. This leads to the leap year.
- The side of the Earth closer to the Sun gets pulled in more than the far side. Because it's constantly rotating, there is a slight, continuous "reshaping" of the Earth by solar gravity. As the insides of Earth move around they experience friction, which bleeds off rotational energy and makes the day get longer and longer over time. So, many years in the future, the length of a day should increase from 1/365.25 years to 1/365 years exactly. An increase of only 0.07%! At that point, you would not need leap years. The problem is that it will not stop there, but keep increasing and then introduce a leap year again. Although, again the process is quite slow, so you can easily have it last entire *anthropic* time periods (thousands of years).
- However, it's also a question of how precise your people are, really. If a year is 365.0001 days, will bother adding a leap year once every millenium? Or will they simply disregard it? As you get more precise with this, the period it lasts for becomes briefer.
- In any case, it would be a bit much to expect *all* the planets in a system to coincide at whole-multiple years. Some of them would surely be fractional even while the others are not. So once your people develop astronomy, they are likely to become disappointed regardless... Unless they place some special importance on their one, precise, home planet.
- Synchronizing lunar and solar calendars is very unlikely, I think. You could always claim it is coincidental, but that's a heck of a coincidence. There might be some tidal effects from the Sun as the two planets are orbiting each other, but these would be much weaker than the one synchronizing the day to the solar year, which is already weak unless the planet is close enough to be scorched like Mercury.
- There is also no reason why the lunar calendar would sync up with the solar *at the same time* as the solar year becoming an integral multiple of the day. These two things are not strongly related, and them co-occurring is even more unlikely than one happening on its own.
- Honestly, if I saw the kind of system you describe, I would suspect that it came about artificially. It's so unlikely to happen in nature that it suggests there was a deliberate manipulation. Changing the orbits of planets implies a very advanced and powerful civilization - so perhaps the "precursor aliens" trope can help you here.
#1: Initial revision
by
matthewsnyder
·
2023-06-22T07:06:44Z (11 months ago)
I think it's unlikely. Colloquially a year is 365 days. But if you actually watch Earth complete an orbit in space, it will not be at the same rotation around its axis at the end as when it started. It actually takes about 365.25 rotations to complete an orbit. This leads to the leap year. The side of the Earth closer to the Sun gets pulled in more than the far side. Because it's constantly rotating, there is a slight, continuous "reshaping" of the Earth by solar gravity. As the insides of Earth move around they experience friction, which bleeds off rotational energy and makes the day get longer and longer over time. So, many years in the future, the length of a day should increase from 1/365.25 years to 1/365 years exactly. An increase of only 0.07%! At that point, you would not need leap years. The problem is that it will not stop there, but keep increasing and then introduce a leap year again. Although, again the process is quite slow, so you can easily have it last entire *anthropic* time periods (thousands of years). However, it's also a question of how precise your people are, really. If a year is 365.0001 days, will bother adding a leap year once every millenium? Or will they simply disregard it? As you get more precise with this, the period it lasts for becomes briefer. In any case, it would be a bit much to expect *all* the planets in a system to coincide at whole-multiple years. Some of them would surely be fractional even while the others are not. So once your people develop astronomy, they are likely to become disappointed regardless... Unless they place some special importance on their one, precise, home planet. Synchronizing lunar and solar calendars is very unlikely, I think. You could always claim it is coincidental, but that's a heck of a coincidence. There might be some tidal effects from the Sun as the two planets are orbiting each other, but these would be much weaker than the one synchronizing the day to the solar year, which is already weak unless the planet is close enough to be scorched like Mercury. There is also no reason why the lunar calendar would sync up with the solar *at the same time* as the solar year becoming an integral multiple of the day. These two things are not strongly related, and them co-occurring is even more unlikely than one happening on its own.