The Erroneous Premise -- Linux Has No Astronomy Software
When I started using Linux some years ago I was at first disappointed that
there didn't seem to be any astronomy programs, particularly planetarium
programs. I'd grown used to a couple in Windows, and I used them for planning
my observing sessions. I could see what Messier objects were up, if any of
Jupiter's moons were soon to transit, etc.
I'm happy to say that I was wrong then, in that there were a few Linux
products around. If fact, there were several, and there are even more and
better products around today.
Use this custom search engine to find astronomy software for you system (try Linux astronomy):
Kstars, the KDE Project's Planetarium Program
One program that I've only recently become aware of is Kstars, part of the educational software under the Linux KDE project. I've found that in many ways Kstars has features I like better than my previous choice.
Kstars is primarily a planetarium program, drawing an interactive map of the
night sky that can be set up for any location on Earth. Stars are shown against
a deep blue background, and relative magnitudes are indicated by star size. The following image is from a portion of a typical Kstars display.
Kstars Screen Shot Segment
Kstars has Extensive Display Control
The magnitude limit of displayed stars can be adjusted. When the user
zooms in to any section of the sky, fainter stars come into view. The
magnitude limit of zoom stars can also be set.
A few catalogs of interesting objects are also available, including the Messier catalog and the NGC catalog. These catalogs can be selectively turned off and on.
The user can elect to have constellation names and lines also drawn on the screen, as well as have bright stars labeled. The Milky Way can be represented by either a simple outline, or by a lightly shaded region as shown in the previous illustration.
Solar system objects can also be turned off and on, including planets, comets, and asteroids. Magnitude limits for these objects can also be selected.
Various guides can selectively be turned on and off, including a horizon
line and a line following the ecliptic. The horizon can also be set to a solid
colored region to mask off stars not visible.
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Kstars has Extensive Viewing Controls
Simply moving the mouse around allows the user to select the Cardinal direction and elevation of view. The scroll wheel on such equipped mice can be used to zoom in to particular areas of interest.
There are a number of short cut keys that aid in controlling the view. Just touching the n, s, e, or w keys move the view to North, South, East, or West for example.
Kstars is Great for Planning Viewing Sessions
Any current display can be printed if desired, and a simple white background
can be chosen for the printed chart. Also, there is a night vision mode,
where the labels and lines are drawn in a subdued red color.
Field of view circles for a few common optical devices are selectable. When
selected, these circles adjust to the zoom level to always give an accurate
indication of field of view. The user can define and name additional fields of
view as desired. In the following image, the white circle represents the field
of view of a common 7x35 pair of binoculars.
Kstars FOV Indicator
You Can Let Kstars Control Your Telescope
Kstars is equipped with drivers for many popular telescopes that allow remote control. Once the proper telescope type is selected, an object of interest can be easily selected for tracking.
Right clicking on an object will bring up a pop up of options. One can view
details about an object, a picture of the object, or select from a list of
links for more information on the object.
Kstars is Extensible
The feature I find most powerful is the ability to add more links to the link list for any selected object. This
makes Kstars extensible in ways beyond most other products.
For example, another product I use, Xephem, has a handy Jupiter viewer that
shows the position of the Great Red Spot and the Galilean moons. Time can be
stepped forward or back to see when these Jupiter features are in desirable
positions. Xephem also has a Mars viewer that displays the portion of Mars
visible to the viewer for any given time.
Kstars has a vertical line chart like that at left for displaying the positions of Jupiter's moons, but it doesn't display any information about the Great Red Spot, and the display is more difficult to interpret than the more visual version presented by Xephem.
Note that the actual Jupiter chart is larger in a Kstars display, but was
shown smaller here for loading efficiency.
Because of the extensible feature of Kstars, I was able to locate good Mars
lists of the respective planets. Now when I click on either of the planets in
the Kstars display and bring up the pop up menu, I get not only the previous