posted
If a planet's yearly cycle took 625 days instead of our accustomed 365, what other differences would the planet logically have from our own?
Just curious, because I was thinking of incorporating this idea into what I'm working on. It's not essential, but the idea interests me enough to ponder.
posted
First are we talking about different size orbit which could effect the temperature of the planet. If it has a larger orbit and it's star is like our sun then there will be a colder climate. You can adjust that by making the star a bit warmer and larger.
You could make the planet rotate faster at almost twice the speed of earth, but that would shorten the actuall number of hours.
If you slow down it's orbital speed then it would have to be justified by some factor to keep it from falling into the star. Since the planet is not already gone it would not be the best explination.
Unless you have to I would suggest not really explaining it unless you can make it hold with the more critical reader who has somewhat of a small clue about how the planets and orbits work.
As for other side effects, none really. The size of the planet determines gravety. Distance from the star helps determine climate. The atmosphere playes into climate also. Orbital speed would should really be irrelavant (could be some small on plannet effects but I don't know of any). Planet rotation determins time of day and night. Moon(s) determine ocean tide effects.
There probably a few more factors that I have forgotten, but that is most of the major ones.
posted
Okay, I'm tired of the way everyone here misuses "effect" and "affect". Both can be used as either nouns or verbs, but the meanings aren't interchangable except in a handful of circumstances.
If you don't know what effect means when used as a verb, or what affect means when used as a noun, then don't use them those ways.
Second, no particular difference, aside from a 625 day year, can logically be inferred from an orbital period of 625 days. I know that this is what has already been said, but I thought I would put it as clearly and concisely as possible.
posted
There are other issues, however. Our seasons are essential a consequence of the tilt of the Earth's rotational axis. If the axis of rotation were much closer to perpendicular to the orbit plane, we wouldn't have seasons, right? (The eccentricity of the orbit, that is, how much it deviates from a perfect circle, is definitely a minor effect. But maybe, if you wanted to completely eliminate seasonal variation, you should posit both a circular orbit and coincidence of the planet's equator with the orbit plane.) So the weather would be the same all the time. That would be an interesting idea to explore. In particular, would a culture that evolved in such an environment even identify a year as a significant unit of time? Would they have learned to look for other, more subtle signs of the planetary orbit (such as the annual migration of the sun through the background of constellations)? If the year is not a primary unit of time for the culture, would they have to invent some other year-like time measure? And if so, what would it be? All interesting ground for exploration IMHO.
Posts: 550 | Registered: Sep 2003
|
posted
Indeed. I will both point out that this is a departure from the topic as initially concieved, and assert that it is a welcome change.
How about a planet with no moon, or several small ones? I do think that the fact that humanity has invented centuries and millenia, as well as observing the week, indicate that a culture developing on a planet with no gross seasonal variation would likely invent a measure of time to fit that time scale. On the other hand, our example indicates that this would be base on simple mathmatical multiplication of the next lowest obvious time indicator or division of the next largest.
I imagine that once constellations have been discovered (which does not seem to inherently depend on the observation of the seasonal year), people would realize that which constellations are visible at what hour of the night, and on which nights, was dependent on a greater cycle. I imagine that astronomers might well calculate this cycle with some accuracy, but I do not imagine that it would be particuarly more important to the average person than...say, the length of a martian year is to us.
Certain people would probably develop some form of navigation or year keeping with such knowledge, but it could not be used for both (in the same way that you can find the remaining side of a triangle, but not two remaining sides).
The more intersting question is what effect lack of seasonal variation would have on the broad climate parameters. Storms on earth are the result of conflicts between ever changing patterns of air and water currents which transfer thermal energy from the ground. Would there be certain perpetual storms on a planet with no weather, along with constant, unvarying winds in most locations and the consequent effects, like minimal variations in the rainfall and cloud cover for any given point on the terrain? Or would day and night alone be sufficient? How long would a day have to be for a given size of planet to provide the disequilibrium necessary to dynamic weather?
The novel I'm working on takes place on a planet with no moon. The biggest consequence of that is that there are no months; the closest equivalent unit of time is a "half-season."
There are also no weeks, since (if you ignore religious reasons) the only reason for a seven-day week is as a proxy for a quarter of a lunar month.
There would also be a difference in tidal effects, because tides are affected by the moon, but lack of a moon would not effect a complete absence of tides because the solar influence is enough to produce tides. (I tried to work in "affect" as a noun, but it really does not make sense in this context, and would have been a mere affectation.)
posted
There are some very cool sites to check out!
http://planetquest.jpl.nasa.gov/science/finding_life.html This one has a neat atlas where you can get information on suns and the planets they host, rotational periods, etc. Unfortunately none listed (yet) are terrestrial - lots of gas giants. There are others.
Also, there are some books that can help. One I've been working on is by Charles Sheffield, called "Borderlands of Science: How to Think Like a Scientist and Write Science Fiction" that I'm using to help with the science of things. I learned why there are limits on what size your star can be (has to do with stability and whether or not it can be called a star).
Back once again to "Crystal Singer" - the planet Ballybran has three moons - the major effect referred to is the "mach storms" but I believe there were others.
Does our moon offer some protection from extrastellar objects - i.e., they hit the moon and not earth?
quote:Does our moon offer some protection from extrastellar objects - i.e., they hit the moon and not earth?
Yes. A number of people have in fact speculated that a large moon is a prerequisite for development of advanced life because of this.
I believe it has much less effect than Jupiter does, though. A system with two Jupiter sized planets in suitable orbits will likely be nearly as stable from this perspective, I think.
One world I'm in the process of generating at the moment has two moons slightly smaller than our own. The only effects I foresee from this are more complex tidal patterns, and the occasional conjunction of the two moons; in my world, major religious festivals are timed to coincide with this occurrence, and the religious calendar is based upon the frequency of the event (question: the frequency would be relatively simple to calculate, assuming simple orbits, right? I'm not quite that up on orbital mechanics...).
quote:If you don't know what effect means when used as a verb, or what affect means when used as a noun, then don't use them those ways.
Yeah, that gets to me to. But I have to say I didn't know that affect could legitimately be used as a noun... having looked it up I can see why. It's quite an unusual word that probably doesn't come up in many circumstances.
posted
Some protection, but not a lot of protection. The chance that an object will hit the moon instead of Earth is fairly remote. Outer gas giants do provide much better protection, but there is no need for a second Jupiter, a single larger gas giant will provide more protection and isn't half so unlikely as two similarly sized gas giants.
Conjunction of two moons would be easy enough to calculate as long as they both had normal orbits seperate from each other and were both fairly small compared to the primary. Put the smaller moon closer to the primary for the best effect on the affect of whoever watches the moons.
To effect an effect that will affect an affect isn't that hard, you see, as long as the affect you're affecting by the effect you effected is the an affect that can be affected by an effect you effect.
Which is to say, whereas the effect that a moon effects on the tides can affect the affect of persons whose affect is affected by the effect on the tides effected by the moon, the discussion of effects affected by affects effected is rather more abstruse.
I suppose if the affects effected were those of a powerful enough race of persons, they could affect the effects of...something.
I think I smell smoke. An effect affecting my affect, so whatever effected that effect...
Printer-friendly view of this topic
