Is there something wrong with this image?

I found it in Wikipedia's article Ecliptic coordinate system and the image's source page is here.

What bothers me is the orientation of the Earth's surface (continents).

  • The horizontal plane with the red line around the sphere represents the plane of the ecliptic. The ecliptic is basically the plane of Earth's orbit around the Sun, in as much as that can be considered to be a plane. (caveats, details, mumble, mumble J2000.0 mumble...)

  • The inclined plane with the blue line is the Celestial Equator, which basically coincides with the Equator of the Earth (...mumble...).

If I understand correctly then, the North pole of the Earth should point in a direction that is perpendicular to the Earth's equator and celestial equator, but it looks to me like this is drawn with the north pole pointing directly up.

Am I wrong, or confused, or both?

Ecliptic coordinate system?

  • 3
    The way "I see the diagram" it looks weird, but it is probably correct. My perception is that it is about frames of reference. We are used to seeing the Earth with Earth's north at the top, not at 23.5 deg from north. This picture has the ecliptic pole at the top. As you state, Earth's equator matches the celestial equator & the Earth's pole would be at right angles to it, in the middle of the white stuff at the top of the Earth. If you imagine a line from this point, perpendicular with the celestial equator it matches 0 deg latitude & is sort of sub parallel with the west coast of Africa. – Fred Oct 10 at 13:37
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    The other thing that might be confusion perception is the representation of the land masses is not accurate. Looking at the representation for Europe, Italy is not present, neither is the Balkan Peninsular or the islands of Britain & Ireland & Scandinavia just look wrong! Though Iceland is present & the Arctic ice extends to far southwards. The last time I looked there wasn't an ice sheet between Iceland & Greenland. Also, the Red Sea isn't represented. – Fred Oct 10 at 13:58
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    The biggest tipoff here is that Africa is "tilted" compared to a regular Mercator map, and that the ecliptic line travels northeastish from Africa, not straight east. However, I agree the other continents are placed somewhat sloppily. – Barry Carter Oct 10 at 17:32
  • @BarryCarter ya, I've deleted my old comments; 0°N, 0°E in the Gulf of Guinea is shown well below the celestial equator, as it should be. – uhoh Oct 10 at 17:34
up vote 5 down vote accepted

The way "I see the diagram" it looks weird, but it is probably correct.

My perception is that it is about frames of reference. We are used to seeing the Earth with Earth's north at the top, not at 23.5 deg from the vertical.

This picture has the ecliptic pole at the top. As you state, Earth's equator matches the celestial equator. The Earth's poles would be at right angles to it and the north pole would be in the middle of the white mass at the top of the Earth - representing the Arctic ice sheet

If you imagine a line from this point, perpendicular with the celestial equator it matches zero degrees latitude and is sort of sub parallel with the west coast of Africa.

The other thing that might be confusing our perception is the representation of the land masses is not accurate.

Looking at the representation for Europe, Italy is not present, neither is the Balkan Peninsular or the islands of Britain & Ireland. Scandinavia just looks wrong! Iceland is present and the Arctic ice extends too far southwards. The last time I looked there wasn't an ice sheet between Iceland & Greenland. Also, the Red Sea isn't represented.

  • You've convinced me. Unless the continents move or the polar ice melts in the photo in the next 24 hours (humor) I'll click accept. Thank you for your help! – uhoh Oct 10 at 17:14
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    @uhoh: Humor accepted any time. :-) – Fred Oct 10 at 17:16
  • The land masses are just highly generalized, because more detail might distract from the main idea of the diagram. OK, maybe a little too generalized.... – Spencer Oct 11 at 1:14

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