So would be possible to have a Hot (Tropical or Arid) North pole and a Cold/polar South pole with a certain planetary set up or geographic set up. I'm open to many ideas, as long as they make this setting possible. Edit: I forgot to mention, I want these area to be livable by humans, as well as the rest of the planet being livable. Would the rest of the planet change in order to do this or do the poles on need to change? THIS PLACE HAS TO BE LIVABLE BY HUMAN WITHOUT FUTURISTIC TECHNOLOGY

  • $\begingroup$ @Molot That question seem like they want the extremes of the temperatures. $\endgroup$ – Nubian Nauzicaa Dec 2 '18 at 17:52
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    $\begingroup$ Please say whether you want to discuss the Magnetic North, the North according to the axis of spin of the Earth or some other north pole. See this article. The Earth Has More Than One North Pole, scientificamerican.com/article/… $\endgroup$ – chasly from UK Dec 2 '18 at 18:31
  • $\begingroup$ @chalet from UK I mean the axis North pole $\endgroup$ – Nubian Nauzicaa Dec 2 '18 at 18:36
  • $\begingroup$ see en.wikipedia.org/wiki/Tidal_locking : if the planet orbits the sun such that one face is always facing the sun (as our Moon does to Earth) it's easy to have one side hot & the other cold if that's all you want, is there any particular reason it has to be the poles? $\endgroup$ – Pelinore Dec 2 '18 at 22:55
  • $\begingroup$ It's a known fact that True North/South and Magnetic North/South are not always the same thing. In fact, the magnetic poles constantly move between the true poles over a course of years (in geological time... it's a pretty fast processes on that time scale, and we can see from the alignment of certain magnetic rocks over time the periods of shift). So one day, your North Pole could be under Florida and the South Pole under the opposite side of the planet directly... though I'm pretty sure this is answering the letter of your question, not the spirit. $\endgroup$ – hszmv Dec 3 '18 at 19:08

I have an idea here; it won't give you the exact effect you're looking for, but it can generate your desired poles at least seasonally. I'm assuming your planet has an Earth-like axial tilt, with seasons and so forth.

Giving your planet an eccentric orbit (oval-shaped, basically, instead of a nice tidy circle like we generally envision them being) and arranging it so that perihelion (the point in the orbit closest to the sun) turns up somewhere near the northern winter, will give you very different temperatures at your two poles. Your northern pole will end up with reasonably even temperatures year-round, because there will be a warmer planet overall during the northern winter to compensate for the reduced sunlight, and the planet will spread that heat to some degree. In the summer, the greater local sunlight is balanced out by a cooler planet overall. Tweak your temperature range properly, and you can reliably manage a warm pole. Your southern pole will be suitably frozen during the winter, but humans have lived in Siberia for thousands of years. In its summer, however, the sun is going to be pouring down the heat: how much in the way of an ice cap will survive, and how much that will compensate for the heat, is beyond my knowledge to reliably answer.

A side effect of doing this is that your seasons will not be of equal length. Your northern winter will be shorter than the northern summer (and the reverse in the southern hemisphere). You're also going to see planet-wide impacts on climate. Expect significantly more seasonal variation in the southern hemisphere (and less of it in the north). Also, the equator is always going to be warmer than the poles on average: if you want to make sure your north pole remains above freezing year-round, your equator is going to be scorching hot and probably very arid. You'll see some people living there, but most of your planet's population is probably going to be in the mid-latitudes.

Also, as a final warning: plants need sunlight to grow, not just heat. Agriculture near the poles, where sunlight will be basically nonexistent for several months a year, is going to be problematic no matter what the temperature is.

  • $\begingroup$ @KJO That's entirely true. My idea here works on the basis that one pole will be closer when the planet is closer: the other pole is facing the sun when the planet is farther away, which obviously will result in less overall warming on that side. $\endgroup$ – Palarran Dec 3 '18 at 3:18

I will say no.

You specify that you are referring to the poles that are on the axis of rotation.

No matter where the poles are there will be no way to get a permanent summer at one pole and winter at the other. For this to happen, one of the poles would have to face the star all year round. You can think of the planet as acting as a giant gyroscope. Even if the planet's axis of rotation is in line with the sun at some point, half a year later the other pole will point at the sun.

Thus each pole will experience a summer and a winter over the course of a year.

Maybe there some other effect that can be exploited to make your scenario work. I can't think of one.

  • $\begingroup$ Precession would do the trick, but I don’t know if it’s geologically possible to set up. $\endgroup$ – Joe Bloggs Dec 2 '18 at 21:39
  • $\begingroup$ @JoeBloggs Precession at this time scale would effectively create a second axis of rotation, which would violate the conservation of angular momentum, IIRC. "No" is the correct answer. $\endgroup$ – rek Dec 2 '18 at 23:02
  • $\begingroup$ @rek: almost all ‘time scale’ arguments can be expressed in terms of energy. I don’t know if a suitable planet can be constructed with a precession, year and day that work while still being human habitable, but I’ve no doubt a suitable planet could be constructed if you get things spinning fast enough and your planet is suitably oblate. $\endgroup$ – Joe Bloggs Dec 3 '18 at 0:03
  • $\begingroup$ @rek why would it "violate the conservation of angular momentum"? $\endgroup$ – ben Dec 3 '18 at 4:09

The effect you’re looking for is precession. Precession is when a spinning object’s axis of rotation varies it’s position over time, cycling round with a constant period. If your plannet precesses with the same period as your year then one pole will be in constant summer, the other in constant winter. They may still be colder than other places on the planet, but one pole will be significantly hotter.

Now: over geological timescales I have no idea if this arrangement can be stable, nor do I know if you can get a planet to precess fast enough to match an orbital period that puts it in a Goldilocks zone without some serious intervention, but at least a physical phenomenon exists that could explain your planet.

  • $\begingroup$ But where will the poles be Joe?, OP says he wants the "axis" poles, so the axis of spin with precession will put the poles where? $\endgroup$ – Pelinore Dec 2 '18 at 23:18
  • $\begingroup$ @Pellinore: one pole will be pointing towards the sun, one away. The link has a wonderfully informative image that should clear up my meaning. $\endgroup$ – Joe Bloggs Dec 2 '18 at 23:55
  • $\begingroup$ I've already seen your link (why would you think I hadn't), it doesn't have a wonderfully informative image (in my view) it's just a gyroscope spinning, a wonderfully informative image would show a representation of the sun with it's satellite (planet in this instance) orbiting & spinning with a couple of cocktail sticks stuck in it labelled north pole & south pole, just call me greedy, I like things on a plate :) $\endgroup$ – Pelinore Dec 3 '18 at 0:19
  • $\begingroup$ There'd be shading on the planet so you can clearly see which side is facing where as it spins & orbits too. $\endgroup$ – Pelinore Dec 3 '18 at 0:23

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