2 added 254 characters in body edited Sep 28 '16 at 8:45 corey979 21.1k66 gold badges4343 silver badges8282 bronze badges f[x_?NumberQ] := MoonPosition[DateObject[{2016, 9, 28, x}]][[2, 1]] FindRoot[Evaluate@f[x]FindRoot[f[x], {x, 12}]  {x -> 17.5595} ListPlot[Table[{x, f[x]}, {x, 1, 24, 0.5}], Frame -> True, FrameLabel -> {"x", "f(x)"}]  So another root is at about 4: FindRoot[f[x], {x, 4}]  {x -> 3.7208} f[x_?NumberQ] := MoonPosition[DateObject[{2016, 9, 28, x}]][[2, 1]] FindRoot[Evaluate@f[x], {x, 12}]  {x -> 17.5595} f[x_?NumberQ] := MoonPosition[DateObject[{2016, 9, 28, x}]][[2, 1]] FindRoot[f[x], {x, 12}]  {x -> 17.5595} ListPlot[Table[{x, f[x]}, {x, 1, 24, 0.5}], Frame -> True, FrameLabel -> {"x", "f(x)"}]  So another root is at about 4: FindRoot[f[x], {x, 4}]  {x -> 3.7208} 1 answered Sep 28 '16 at 8:33 corey979 21.1k66 gold badges4343 silver badges8282 bronze badges f[x_?NumberQ] := MoonPosition[DateObject[{2016, 9, 28, x}]][[2, 1]] FindRoot[Evaluate@f[x], {x, 12}]  {x -> 17.5595}