# corrected projections: Is this world map realistic? I tried to use plate tectonics to inform my mountain and island chain placements

1 degree of latitude = 96.57 km.

Equirectangular projections. (Yes, I need to revise the polar regions to make sure they don't get squished.)

Obliquity of Jasmi: +31.1 degrees.

Marked (too vaguely, I know,) are the equator, 31.1 degrees, 40 degrees and 58.9 degrees (my tropical and polar circles, as well as my subtropic/temperate regions).

Disregard the colors on the top map if you like; in a previous iteration of my planet's flora evolutionary timeline, I made this map to highlight diverse species of algae blooms around my continents.

Lighter color = higher elevation in the second map

Thanks! <3 R

• Without seeing the sea-floor and some elevation data any answer I could give would be a guess. – Ash Feb 19 '18 at 12:18
• @Ash I tried to indicate where the mountains would be, but I honestly don't know where to begin with realistic elevation data. My planetary radius is 0.870 R(earth), and my mass is 0.602 M(earth) if that helps at all. – Rúnatál Davino Feb 19 '18 at 12:21
• Sorry didn't mean to imply hard altitude data, but relative elevations tell you a lot about the tectonic and geological systems that underpin a map. The seafloor tells you more about tectonic structure than the land too. – Ash Feb 19 '18 at 12:30
• You will have to show us the actual plate boundaries. Without showing us the plate boundaries, the answer-er will have to make them up by themselves. That means that each answer can have its own imagined plate boundaries, so the answers will be 'primarily opinion based.' I'm going to say that it looks good to me, but I will vote to close this question as opinion based. – kingledion Feb 19 '18 at 13:21
• Have you seen this? It may help: worldbuilding.meta.stackexchange.com/questions/2594/… – Tim B Feb 19 '18 at 13:21

# Your surface is too small

Radius is given as $0.87 R_{Earth}$, so we expect an equatorial circumference of $0.87\times2\pi R_{Earth}=34826km$

Boston to LA is 2992 Miles (4815.2 km), your equatorial continent fits about five times into the map you've provided giving us only 24076km.

So your map is missing about ten thousand kilometers of space for the size planet you wanted.

• Thank you! Looks like my BOTE calculation failed me. Would you suggest adding more space in the map, or just re-calculating the size of that one continent? It occurs to me that the dimensions of my map are probably not ideal for an equirectangular projection. I'm very new to mapmaking. – Rúnatál Davino Feb 19 '18 at 16:30
• It really depends on what you want the world for. At first glance this was all I could see that was wrong with it. – Lio Elbammalf Feb 19 '18 at 16:35
• both I'd say...first off, an equiectangular map, naturally, needs a 2:1 size ratio to make sense. there's a catch though, as with all map projections: this one distorts distances (e.g. google/openstreetmap distorts area), to a significant higher degree with higher your latitudes (if you draw a circle on the map and two radius lines at 90° and 180°, actual length in map units for the latter will be roughly 1.4 times longer). areal distortion, however, will be much more abstract to design I think (the northern continent would roughly be half the size/area than it appears on the map) – t.ry Feb 19 '18 at 17:29
• @t.ry I have added more area to the map to make the projection make sense! – Rúnatál Davino Feb 19 '18 at 19:01

If your planet's orbit parameters are anything like Earth's there would supposedly be some ice sheets on the poles.
Update: Ice is not necessary, as mentioned in the comments below. Maybe a nice to have though, don´t know if that would actually fit your story.

Maybe even land due to equatorial buldge (I refer specifically to the water mass...theres lot's of oceans to buldge there, and much space at the equator to flow to).

I could also imagine massive global storms and extremely strong circumpolar currents as a result.
This is what I could do with both your maps:

• heights are scaled to -7000m and 6000m (i.e. roughly two thirds of Earth's min/max)
• I georeferenced both pictures onto a sphere according to your planet's size and used a modified Robinson projection for this

• derived height map: Note: according to your picture, significant parts of your ocean would be higher than the continents...

• mashup, color relief and superimposed world image: Note: colors don't really make sense, but with that elevation model I couldn´t help it. The landmasses are more or less uniform and mostly level with the surrounding ocean (at 2000m...), so the shaded relief has not much effect here

But it looks quite good. Not too bad at least. I had no time for magic...
Also, I´m not sure if this does have anything to do with the question...but: maps.

• Polar ice isn't a necessity. During the Cretaceous, Earth didn't have permanent polar ice caps. There's some data suggesting that in the Arctic and Antarctic regions there may have only been persistent ice in areas 1000+ meters above sea level. – Keith Morrison Feb 19 '18 at 23:23
• We are currently in an 'ice age'. For most of Earth's history there were not permanent ice caps. The current ice age started about 33 million years ago, when Antarctica was isolated, and the Antarctic ice cap formed. Before then, there was no permanent ice cap for hundreds of millions of years. There may be some connection with continental position and ice cap formation. Since the OP's map does not have a polar continent, it may not have ice caps either. – kingledion Feb 20 '18 at 2:03