Do they just use the side of the solar plane which Earth uses as North and then adopt that based on the planets inclination? And how does this work for Pluto that is not on the solar plane? So how did they determine Mars North and South poll positions.
2007-01-08 14:31:28 · 5 answers · asked by Richard R 1 in Science & Mathematics ➔ Astronomy & Space
North is determined relative to the direction that planet rotates.
2007-01-08 14:39:39 · answer #1 · answered by The Maestro 4 · 0⤊ 0⤋
You bring up an interesting point, actually. First, we want a definition that works for moons as well as planets, since you want to define north/south/east/west for them as well. After all, the objects in our solar system with the best chance of supporting life in the future are the moons of the outer planets, not the outer planets themselves.
Now, defining the north-south direction by the axis of rotation doesn't work for all planets and moons, since not all of them rotate. One of them is our moon, of course. Given that, which way would be considered north on the moon? I suppose one option is to make the north/south direction perpendicular to the moon's orbital plane. (You might note, however, that the Earth's axis is NOT perpendicular to the oribital plane - it's tilted at a 23.5 degree angle. So, we can't use this definition for all planets and moons.)
Also, defining north as "up" is purely arbitrary, which in itself isn't a big deal. However, another poster says that, on the other planets and moons, "up" is defined by the counterclockwise direction of rotation. OK, that sounds reasonable; however, it also means that, for the planets which spin clockwise (i.e. Venus and Uranus), north will be upside down, in effect.
2007-01-08 16:25:15 · answer #2 · answered by Anonymous · 0⤊ 0⤋
This issue was decided by the IAU a while back. It was decided that the pole of a planet that can be observed to have the rotation of counter-clockwise when viewed from a distance above said pole, will be defined as north, and the other pole that rotates clock-wise shall be defined as south. I hope this helps.
2007-01-08 14:52:16 · answer #3 · answered by Sciencenut 7 · 0⤊ 0⤋
As long as the planet rotates in the same direction as Earth, they use the same direction from the elliptic plane. They reverse the poles if it rotates in the opposite direction.
2007-01-08 14:38:48 · answer #4 · answered by Sophist 7 · 1⤊ 0⤋
okay.. first of all, north is up and south is down. duh
2007-01-08 14:41:15 · answer #5 · answered by YoungMoney 2 · 0⤊ 0⤋