Unnatural seasons

Although I’m still plugging away at editing The Ashes of Home, I’ve started turning my mind to a new project. Tentatively titled The Long Dark, this is another far-future story but set in a universe very different from Shayla’s.

More to the point, it’s set on a world rather different from anything we normally read about. For some reason, I had it in my mind that it would be fun to set a story on a planet with a 90 degree axial tilt.

What the heck does that mean?

Well, our Earth has a 23 degree axial tilt, which means that at midsummer/midwinter the poles are tilted 23 degrees towards or away from the sun. This tilt gives us our seasons.

Near the equator, day and night are roughly the same length no matter what time of year it is. But the further away from the equator you go, the greater the difference between summer and winter hours of daylight. When you cross the Arctic or Antarctic circles - lines of latitude 23 degrees down from the poles - something strange happens. You get periods of round-the-clock daylight and darkness. The closer to the poles you travel, the longer those spells of continuous light and dark last. The poles themselves experience close to six months each of light and six months of dark.

If your planet has a tilt of 90 degrees rather than 23, this picture is taken to extremes. The Arctic and Antarctic circles would actually run along the equator, and everywhere other than the equator will be a “land of the midnight sun”.

Because the planet’s spin is in line with the plane of its orbit, the motion of the sun will look very strange compared with what we are used to. At midsummer, the planet’s axis is pointing right at the sun, so the sun will be stationary in the sky - direct overhead at the summer pole, or hovering on the horizon if you’re at the equator. This will make for ferociously long and hot summers at the poles.

As the year progresses, the sun will start to move in increasingly large circles in the sky, a bit like the handle of a spinning top that’s losing speed and starting to topple over. Sooner or later, depending on what latitude you’re at, those circles will start dipping below the horizon and you’ll get a few weeks or months of a true day/night cycle ... until the sun vanishes below the horizon for good and you go into a much longer night.

Which is where the title comes from.