--- a/extra/mapping/NEWS	Sat Mar 09 17:51:15 2013 +0000
+++ b/extra/mapping/NEWS	Sat Mar 09 18:06:20 2013 +0000
@@ -1,6 +1,13 @@
 Summary of important user-visible changes for mapping 1.2.0:
 -------------------------------------------------------------------
 
+ ** The following functions are new in mapping 1.2.0:
+
+      deg2km
+
  ** The function `distance' has been greatly improved with more options
     including calculating the azimuth between points and support different
     angle units.
+
+ ** The function km2deg can accept an optional radius or the name of some
+    Solar System objects.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extra/mapping/inst/deg2km.m	Sat Mar 09 18:06:20 2013 +0000
@@ -0,0 +1,48 @@
+## Copyright (C) 2013 Carnë Draug <carandraug@octave.org>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {@var{km} =} deg2km (@var{deg})
+## @deftypefnx {Function File} {@var{km} =} deg2km (@var{deg}, @var{radius})
+## @deftypefnx {Function File} {@var{km} =} deg2km (@var{deg}, @var{sphere})
+## Convert angle to distance.
+##
+## Calculates the distances @var{km} in a sphere with @var{radius} (also in
+## kilometers) for the angles @var{deg}.  If unspecified, radius defaults to
+## 6371, the mean radius of Earth.
+##
+## Alternatively, @var{sphere} can be one of "sun", "mercury", "venus", "earth",
+## "moon", "mars", "jupiter", "saturn", "uranus", "neptune", or "pluto", in
+## which case radius will be set to that object mean radius.
+##
+## @seealso{km2deg}
+## @end deftypefn
+
+## Author: Alexander Barth <barth.alexander@gmail.com>
+
+function km = deg2km (deg, radius = "earth")
+  if (nargin < 1 || nargin > 2)
+    print_usage();
+  elseif (ischar (radius))
+    radius = spheres_radius (radius);
+  elseif (! isnumeric (radius) || ! isscalar (radius))
+    error ("deg2km: RADIUS must be a numeric scalar");
+  endif
+  km = (deg * pi * radius) / 180;
+endfunction
+
+%!assert (km2deg (deg2km (10)), 10)
+%!assert (km2deg (deg2km (10, 80), 80), 10)
+%!assert (km2deg (deg2km (10, "pluto"), "pluto"), 10)