XMoontool for X11/Motif
Here you find a version of John Walker's
Originally written as a SunView application in 1987, the code was put into
the public domain so that several variants of this software can be found on
Especially, in 1993 it was ported to X11/Motif and made available for Linux
as xmoontool 3.0.1 by Cary Sandvig.
What you can download below is a revised and slightly modified version of this
port. The current release is named xmoontool 3.0.3.
Compared to the 1993 version the most notable changes are as follows:
See a sample screenshot how it comes out for
The Julian date is displayed accordant with the astronomical standard.
The phase times (new and full moon, first and last quarter) are shown
in local time.
Color mode is enabled by default.
"Age of moon" has been fixed and returns the time elapsed
in the current lunation.
The colored moon is depicted completely darkened for several hours
Introducing refined methods for reckoning celestial positions
(cf. section XMoontool enhanced below).
`-U` added to have distances expressed in miles
rather than kilometers.
While the phase information given by the original program is fairly correct,
this cannot generally be stated for the lunar and solar distances.
With v3.0.3 an effort has been made to establish an improvement in this
respect. There are now two different computational models offered to
accomplish this task:
The decision which model to use is to be made when building the xmoontool
- (a) The internal model
A low accuracy replacement of the original formulae, taking a few more
perturbations of the moon's orbit into account. Aside from giving
moderately better results, this approach has a detailed online
documentation as it is derived from the description in Paul Schlyter's
on computing planetary positions. (Paul Schlyter's home page
besides an excellent starting point for folks who wish to learn more on
related astronomical topics.)
- (b) The libnova model
A high accuracy approach with error bounds even acceptable for serious
astronomical purposes. If you need to manually download libnova, get it
It should be mentioned that the libnova code contains a number of GNU
extensions, and building the library might require some patching on
systems whose libc is not GNU. Anyway, if you are in trouble with libnova
or just don't care about the moon's exact distance and visual size, you
can safely choose alternative (a). As far as the lunar phases are concerned
you won't experience much difference.
"WITHOUT_LIBNOVA=yes" is set in the build environment
then (a) is chosen, otherwise (b) is assumed; see the installation
instructions for further details.
FreeBSD users are referred to the ports collection or may install
a binary package via
`pkg_add -r xmoontool`.
For other flavors of Unix you can download the
extract the gzipped archive, and use
`make` to build the
Also see the README for the complete installation
Be reminded that, aside from the X11 libraries, the Motif toolkit is required
to build and run this software. At least one of open-motif or
lesstif appears to be shipped with virtually every contemporary
software collection for Unix-like operating systems.
Ensure to have a corresponding package installed prior to executing
Last updated: 2006-03-01
© 2006 Frank W. Josellis