Xplanet, a renderer for planetary and solar system images based on 
The NASA Spice Toolkit, release 1.3.1 for OS/2.

Xplanet is a solar system simulator which calculates accurate positions 
for the major planets and satellites and generate images rich of features 
based on the NASA SPICE Toolkit.

Xplanet is capable of producing various types of graphics depicting the 
solar system. 

Xplanet was inspired by Xearth, which renders an image of the earth 
into the X root window. 

All of the major planets and most satellites can be drawn, similar to the 
program "Solar System Simulator":http://space.jpl.nasa.gov/. 

A number of different map projections are also supported, including azimuthal, 
Lambert, Mercator, Mollweide, orthographic, and rectangular.

For fun, it is normally used to create computer wallpapers, which may be updated 
with the latest cloud maps or the regions of Earth which are in sunlight,
but its usefulness goes far beyond:

The NASA Spice system is an ancillary information system that provides 
scientists and engineers the capability to include space geometry and 
event data into mission design, science observation planning, and 
science data analysis software.

The principle components of the SPICE system are SPICE Toolkit software 
and SPICE data files-often called "kernels."

SPICE is used throughout NASA and within many other U.S. and international 
agencies for organizing, distributing, and accessing ancillary data associated 
with space science missions. 

The NAIF website contains the few important rules regarding using SPICE. 
If of your interest, please take a moment to read these.

Xplanet generates images using this data, so more data kernels you provide, 
more precision you get on output.

Changelogs from previous 1.3.0 release (27/10/2015):
+ Added missing support for Netpbm graphic formats (ppm, pgm, pbm);
* Latest trunk include updates to Giflib 5.0.0 (static link).

Of course a rexx gui could be usefull, depend on free time, you're free 
to provide one, meanwhile, there is a java gui here:

https://sourceforge.net/projects/xplanetconfig/
no tested, but with a minimal effort it could be usable.

This package contain only base data, you need to provide more 
maps and data kernels to NASA Spice system: keep in mind
that providing more data you can is equal to a more precision 
and a more detailed output!

Thanks for your feedbacks and suggestions :-)!

You should need some dll (and related dependencies), this is the complete list 
of all packages containing main dynamic libs (dll) you should have to use 
Xplanet release 1.3.1:

ftp://ftp.netlabs.org/pub/gcc/gcc4core-1_3_1.wpi (*.dll)
ftp://ftp.netlabs.org/pub/gcc/libc-0.6.6-csd6.zip (*.dll)
http://rpm.netlabs.org/release/00/zip/urpo-20150513-11_oc00.zip (urpo.dll)
http://rpm.netlabs.org/release/00/zip/pthread-20150408-19_oc00.zip (pthr01.dll)
http://rpm.netlabs.org/release/00/zip/zlib-1_2_5-5_oc00.zip (z.dll)
http://rpm.netlabs.org/release/00/zip/libjpeg-8c-1_oc00.zip (jpeg.dll)
http://rpm.netlabs.org/release/00/zip/libpng-1_6_21-3_oc00.zip (png1616.dll)
http://rpm.netlabs.org/release/00/zip/libtiff-3_9_5-1_oc00.zip (tiff.dll)
http://rpm.netlabs.org/release/00/zip/gettext-0_18_1_1-7_oc00.zip (*.dll)
http://rpm.netlabs.org/release/00/zip/freetype-2_6_3-1_oc00.zip
http://rpm.netlabs.org/release/00/zip/pango-1_28_4-1_oc00.zip
http://rpm.netlabs.org/release/00/zip/glib2-2_33_12-5_oc00.zip

For netlabs.org's yum/rpm users: 

yum install libc libssp libgcc1 libgcc-fwd libstdc++6 libsupc++6 
yum install libjpeg libtiff urpo gettext libpng pthread zlib 
yum install freetype pango libglib

Will install all main necessary packages.

To install as user, usually executables and libs should be respectively somewhere 
in path and in libpath statements.

Xplanet has been build disabling X system, the only output available are png, 
jpg, tiff, ppm, pgm, pbm and gif formats and it will not work on Xorg for OS/2.

More infos, source code, maps and data kernels for the NASA Spice system 
are available at:
http://xplanet.sourceforge.net/
http://hans.ecke.ws/xplanet/
http://naif.jpl.nasa.gov/naif/
http://naif.jpl.nasa.gov/naif/aboutspice.html
ftp://naif.jpl.nasa.gov/pub/
See also the README file by the author, Hari Nair.

Gianfilippo Cimmino (gianfli.cim@gmail.com)