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108

In theory, the answer is actually yes. However, unlike our own planet, whose seasons are created through tilt, the planet in question would have to have an elliptical orbit that brought it closer to its sun during certain parts of the year and further away during other parts of the year. The regularity of the orbit would create stable season times. This ...


57

An even simpler explanation is simply for there to be no land in one hemisphere of the planet. If it’s summer in the southern hemisphere, then no one will care that it’s winter in the northern hemisphere if there is no land and therefore no people. Seasons will be stated as affecting the whole planet even if it’s not technically true. They might affect a few ...


46

Yes and no. This NASA page has a good summary of why we have seasons (emphasis mine): It is true that Earth’s orbit is not a perfect circle. It is a bit lop-sided. During part of the year, Earth is closer to the Sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the Sun and summer when it is ...


33

I'm surprised no one mentioned Sitnikov planets yet. Image found on Wikipedia. There is a very unlikely constellation in which a planet moves along the axis through the centre of gravity of a binary star system. In such a system, the planet can oscillate chaotically which, given a tilted rotation axis of the planet, would lead to seasons of varying length. ...


30

The reason we have four seasons is directly related to our planet's axial tilt... the rotational axis of the Earth is currently [1] inclined at 23.5° from the "vertical" relative to our orbital plane: Summer is the season in which a given hemisphere is tilted more towards the sun, Winter is the season in which a given hemisphere is tilted away, and Spring ...


26

Get rid of the "gathers" part of "hunter-gather" and make the people to be carnivorous; At least like wolves are, if not obligate carnivores. That would greatly increase the gap between where agriculture becomes more advantageous than a nomadic hunting/herding lifestyle. Most likely they would still pick up skill and knowledge to care for the herd, and ...


20

An alternate explanation would be a binary star system. While the two stars orbit eachother, they get closer and further away from the planet, producing more and less heat. This allows for seasons of equal length, while an elliptical orbit would have a short warm season, and a longer cold season, as the orbital velocity of the planet is greatest at its ...


18

The planet has no axial tilt. But it anyway has seasons, because: The star it orbits arount is an intrinsic variable star, it changes its size and brightness periodically, causing seasons that may repeat multiple times per year, since the star may change its brightness multiple times per year. Variable star at different times: therefore, differing from ...


17

Sure you could have an erratic orbit. This is an orbit that has the planet coming sigifigantly closer to the sun at one point and then much further at its opposite but that the orbit is moving as well. In this way you could have a winter that is much longer than another and then a very long summer. This would be predictable once you understand the physics ...


17

Imagine a planet with two life layers: Outer space ... Rather dense atmosphere with floating moss performing photosythesis ... Hard earth crust, with not enough light for efficient photosynthesis Every once in a while, a huge (Paris-sized) lump of moss gets too heavy and falls down, triggering all herbivore animals 1000 kilometers around to wake up from ...


15

The year is related to the motion of the planet around its star. When the star are back to a certain position, one says 1 year has passed. To account for season length which are in the range you ask, you could have a sort of variable star with small variation of intrinsic luminosity on an irregular period. When the luminosity is at its peak, you have the ...


14

I'll offer a substantially different approach from what has been said so far. The orbit of your planet doesn't necessarily need to be eccentric or instable and neither does it need a rapidly oscillating axis of rotation. The cause of these fluctuations in temperature could be similar to our earth's ENSO which is a global phenomenon where the surface ...


14

To avoid too much confusion I am going to state some of my assumptions. I had to edit my answer slightly, to take into account some factors I had realised over the few hours since I posted my original answer. If people don't agree, I can always roll back. I still hold by my answer, although I do think altitude will actually be the biggest factor affecting ...


13

Co-orbital configuration It is possible for a planet to change its orbit every so often, resulting in the length of a year changing. This is just one more example among the many answers here of something that could cause seasons to lengthen and shorten in a cycle. An example of a planet that has this property is the Earth. Our planet is in a co-orbital ...


13

Your seasons aren’t caused by axial tilt. They’re more accurately known as ‘weather’. There is a system on Earth that leads to warm, humid seasonality and raised sea levels on top of the usual four seasons caused by tilt relative to the sun. It is called El Niño/ La Niña, and (to simplify greatly) it's a giant wave that bounces up and down the planet’s ...


13

The ocean itself tends to moderate climate -- Vancouver, BC, gets much less severe winters than Toronto, despite being somewhat further from the equator. Further, the temperature of the water has a strong effect -- Sheffield (England) would have a climate like Yellowknife if not for the tail end of the Gulf Stream warming the winters. So, that's what you ...


12

The four seasons are a convention which works best at temperate latitudes in Europe and the Americas. Our ancestors could have as easily agreed on six or eight. In many temperate and temperate-continental places there is actually a clear difference between the first part of what is usually called autumn and the second part: that would make five. In my ...


12

First it needs to be noted, that for the entire planet to have same season it needs to have its rotational axis be perpendicular to its orbital plane. As for how it can have changing seasons there're a couple ways: Previously mentioned in one of the answers elliptic orbit. For earth-like seasonal difference the furthest point should be maybe 1.4 times ...


11

There are several options (as detailed by the answers on this page), but one of the most possible with an Earth-like set-up, is an eccentric orbit heavily affected by surrounding planets and the planet's sun. The majority of this post is a reference from Dr. Irv. Boomberg, of the University of Toronto, Canada, from this page, of special interest is this ...


11

A meta answer for any question of the form "How can I have a planet where civilization doesn't look like ours?" is "Read Jared Diamond's book Guns, Germs and Steel and figure out what links to cut to stop us developing as we did. Our agriculture is primarily based around a very few grains (wheat, rice and, to a lesser extent, barley, maize and millet) and a ...


9

You orbit a double star, one of which is much dimmer than the other. This causes the "brighter" star to come closer/further away in a period faster than your "year". The dimmer double star is dim enough that you cannot practically see it as a star; it is washed out. At best, it might appear as a faint ghost at dawn/dusk. Also, the dim star would rarely ...


9

Not only can it be done, but you're basically describing Vancouver Island. Vancouver Island has extremely mild winters and warm (but not hot) summers. Most conveniently for the purposes of your story, you don't even have to add a new island to the Earth to make your story work. It's been often speculated (although not proven) that explorers from Korea and ...


8

Our orbit and our sun's output are fairly constant. The sun does however, have a very large impact on our weather, both on a daily basis and over a much longer period of time. The sun has a cycle as well, where it has a 'hot' and 'cold' cycle. A sun with more varied and unstable cycles could very well lengthen or shorten a season, mostly noticeably winter ...


8

Yes, more eccentric orbits are possible and you can find or handwave reasons for it to stay that way (e.g. pumping from gas giant). In fact, this is expected to be the case for inner planets around dim red stars (much closer than Earth is to our sun to get the same total light) when a giant is also present farther out. Interestingly, the day will be ...


8

I'm going to attack this with math. First off, I am not going to make any assumptions about what orbits might be stable. That is something we can check with an orbit simulator like rebound, as I did in this question. Instead, I will assume there is a stable orbit around two suns of equal mass and luminosity. The orbital profile will be a perfect circle (0 ...


8

Entire planets don't have the same seasons Here is a climate data graph for Singapore. Singapore only has one season, hot and wet. The average monthly temperature is between 22.3 and 23.3 C every month, and there is always more than 160mm of rain. But, obviously, there are seasons in other places on the Earth. The mid-latitudes have summer and winter; the ...


8

Lets start with (4). To have day/night cycles the planet must rotate and there must be a local sun (or suns) of some sort typically at less than 90 degrees from the planet's rotation. Check. Add (2). With the sun overhead(ish) at the equator, in order to be cold there the day/night sun needs to far enough away that its average heating during a day is less ...


8

I'd suggest something along the lines of El Niño/La Niña - complex, hard to predict phenomena that can minimize or intensify global weather patterns. For Earth, they can last 2 to 7 years, and effect all seasons across multiple continents. Granted, they don't completely delete seasons, but it's not hard to imagine their effect being more pronounced and/or ...


7

No, the length of the year has no effect on the seasons other than their respective duration. Seasons are caused by the axial tilt of the Earth, not by the length of the year. The length of the year only determines how long the seasons are in absolute terms, but their relative duration would still be the same. Spring would still be a quarter of the year, ...


7

With the right planetary and orbital configurations season lengths could easily vary. Two possibilities come to mind: A much larger planet with a orbit slightly more eliptical than the target planet but fairly close; this would cause perturbations in the orbit of the smaller inner planet. However it would not be a fast thing. Also at least using earth as ...


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