I'm trying to plot the Earth position with the Sun in the origin. I have two lists like this:

sun = {Subscript[M, S], e0sun = AstronomicalData["Sun", "Position"],v0sun = {0, 0}};
earth = {Subscript[M, T],e0earth = AstronomicalData["Earth", "Position"],v0earth = {0, 0}};

Where the first component is the mass, the second one is the position and the third one is the velocity(I will change this value later).And I have the function position like this:

position[{x1_, x2_, x3_}] = x2;

So the position function for earth and sun returns:

$$\{1.61307\times 10^{10} \text{m},1.46355\times 10^{11} \text{m},241710. \text{m}\}$$ $$\{0 \text{m},0 \text{m},0 \text{m}\}$$

When I try to plot both I do this:

S1 = Graphics3D[Point[position[earth]]];
S2 = Graphics3D[Point[position[sun]]];
Show[S1, S2, Axes -> True]

But I get an error because of the units, I think. I solved it doing:

S1 = Graphics3D[Point[{position[earth][[1, 1]], position[earth][[2, 1]],position[earth][[3, 1]]}]];

And the same for the sun, but I would like to find a better way with the units.

  • $\begingroup$ I'm not sure about what you're trying to do with position[Array[x, Length[earth]]] = x[2], but it seems wrong to me $\endgroup$ Dec 15, 2014 at 19:59
  • $\begingroup$ You are right, @belisarius, I already changed it. $\endgroup$
    – Danowsky
    Dec 15, 2014 at 20:17

1 Answer 1


You could pick a unit for your coordinates and divide through by it:

S1 = Graphics3D[Point[position[earth]/Quantity[10^6, "Kilometers"]]];
S2 = Graphics3D[Point[position[sun]/Quantity[10^6, "Kilometers"]]];
Show[S1, S2,
 Axes -> True,
 AxesLabel -> Table[Quantity[HoldForm[10^6], "Kilometers"], {3}]]

Mathematica graphics

Or somewhat fancier:

Format[powerForm[quantity_Quantity, base_: 10]] ^:= 
  With[{p = Log[base, First@quantity]}, 
   Quantity[HoldForm[base^p], Last@quantity]];

units = Quantity[10^6, "Kilometers"];
S1 = Graphics3D[Point[position[earth]/units]];
S2 = Graphics3D[Point[position[sun]/units]];
Show[S1, S2,
 Axes -> True,
 AxesLabel -> Table[powerForm@units, {3}]]

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.