Needed - a modified map of the Earth

[ffutures]

I've looked at the various options for changing the position of the Earth's axis - see previous posts - and decided that I'm going to go with a relatively small change, moving the North Pole about 15 degrees south along the 180 degree meridian, a little west and north of the Bering strait between Alaska and Siberia. This means that London is now at 35 degrees north, not 50 degrees, so hopefully enjoys a mediterranean climate (about the same as Algiers). The North Polar ice cap is probably going to end up close to or touching Siberia and Alaska, but they're used to cold weather there anyway, while the South Pole moves closer to the tip of Africa, and hopefully nothing too drastic happens to the rest of the world. It's still going to be a more or less recognizable map, just a bit distorted.

Niamey in Niger is now on the equator, I think the northern tip of Australia is too, Ecuador is now very slightly south of it, and so forth. You can visualise this to some extent as a sine wave plotted on a normal map of the Earth, with the peaks 15 degrees North of the current equator at the Greenwich Meridian, 15 degrees south at 180 degrees.

The snag is that what I will need is a map of the earth plotted with the new equator as a straight line, and the land masses shifted accordingly. I can probably fake this to some extent by distorting a normal map, but all map projections lie to some extent about the position and size of land masses near the poles, and changing their position without changing the relative sizes will make this worse. I'm not enough of a geographer to get this right. If anyone has software or the skills to do this properly, or can think of a better way to do it, I'd love to hear from you.

I'm not too sure what to do about the degree of axial tilt. 20 degrees or so seems to work well for having seasons and forming nice big ice caps, but would anyone stupid enough to do this in the first place think of that?

Comments

[keristor.livejournal.com]

I was going to ask about the axial tilt. Too small and you get less severe seasons, but on the other hand the north and south are permanently cold (at the current latitude of Scotland, for instance, it would be permanantly like March and not very habitable) and the tropics are wider. Too large and the Arctic and Antarctic Circles move towards the equator, giving warmer summers (more area direct sunlight but colder winters. 20-25 degrees seems a good compromise.

(This is something a lot of SF, and especially visual media SF, gets wrong, with "desert planets" and "forest planets" and the like. You can't have a planet which only has one sort of terrain except in very unusual conditions, like being in a close orbit round a cool star where the solar orbit time is on the same order as the rotation of the planet and with high axial tilt, and in that situation any concept of 'day' and 'night' would be definitely strange. It's dubious if such a planet would be very colonisable. But I digress...)

As for the map, it sounds as though you want a Mercator or similar projection with your altered poles and equator. What you need, therefore, is a 'map' being a full spherical list of coordinates, rotate those (simple trig, just tedious), and then re-project (again, simple trig). The big problem is getting that map in the first place (note that you need the solid ground, having removed the icecaps, then you replace those afterwards).

If someone has such coordinate map, I would be /very/ interested in getting such a list. The alternative, as you say, is to try to reverse engineer them from a standard projection but you'll lose details round the poles.

(Hmm, the BBC must have such a map, for the rotating Earth graphic which they have sometimes morphed into a tumbling cube etc. Possibly not much detail, though.)

Note that the Arctic cap will have become largely open sea on the Atlantic side, and possibly down to Japan on the other side.

[nelc.livejournal.com]

I think what I'd do is get a cheap globe from somewhere (Early Learning Centre, maybe) and redraw the equator, major lines of latitude and poles on it in marker, then make illustrations from that. Or photocopy one of the 'peeled-orange' equal area projections from an atlas, cut out and assemble as a sphere, and do the same. Alternatively, do it in a 3D package with a free globe.

I've been trying to think how to do it with maps and the polar projection filter in Photoshop, but I can't quite visualise it. Take a map of the globe, convert to polar co-ords, displace by eye, then convert to Cartesian. Might work, but going from Mercator is going to leave a pair of holes over the poles, plus I don't think Mercator is the right projection to use.

[nelc.livejournal.com]

How big in pixels would you need it to be?

[doc-mystery.livejournal.com]

After a bit of searching (since I remembered someone else doing this), here's this link which may help you:

http://www.worlddreambank.org/T/TILT.HTM

::B::

[dandello.livejournal.com]

My one concern is the Icecaps - shifting those it may create unexpected changes in the ocean currents which will, in turn, create other climate changes.

[whswhs.livejournal.com]

I don't think he offers tools such as you need, but you might like to take a look at Planetocopia (http://www.worlddreambank.org/P/PLANETS.HTM) for some ideas along the same lines.

Late, but ...

[history-monk.livejournal.com]

How is the pole shift actually being accomplished? There's, well, quite a lot of momentum that needs to be changed.

Verne's The Conquest of the North Pole has a description of what would happen if it were done with a single blow, which can be summarised as "quite a bit like a big enough asteroid impact to do the job". The earthquakes and tidal waves would be far beyond anything that happens when the planet is left to itself.