More Free Software for Christmas

In my previous posting I gave you the links for two of the best flight simulator programs available on the Internet. In today's posting, I'll introduce you to what I feel are the two best astronomy/planetarium packages you can find at any price. And, like the previously-discussed flight simulator programs, the two packages mentioned below are also 100% free!

Stellarium

As a writer, one of the things I've learned over the years is that practically all children (and most adults) are naturally curious about the beauty of the night sky. Until relatively recently, to actually know what you and /or your kids were looking at involved finding a book with drawings of the night sky, dragging it outside, and then trying to align the book with the stars. If you have ever tried this, you know how hard such a seemingly simple task can be. If you and your kids want to avoid spending time outside in sub-freezing temperatures, you definitely will be interested in Stellarium.

Stellarium is probably the best open source (read "free") general astronomy program that I've found. It works in real time, meaning that it gets the date and time from your operating system's internal clock and then creates a computer-generated image of what the sky outside looks like where you live, at that particular time, and in any direction that you might look. Although that , in itself, is impressive; to get an idea of how sophisticated Stellarium actually is you really should take a look at the screenshots page and then read the downloadable (97 pages, PDF) Stellarium User's Guide . I promise you that you will be impressed!

Like practically all other software packages, Stellarium's functionality can be enhanced with a number of addon packages that do everything from changing the date and time for different locations to showing the paths of artificial earth satellites such as the International Space Station or the Hubble Telescope. A list of these addons can be found within the Stellarium Wiki pages .

Stellarium can be downloaded from the links provided on its homepage and is available for all major operating systems, including Windows, Linux, and Mac OSX.

Celestia

On its homepage, Celestia is described as "The free space simulation that lets you explore our universe in three dimensions." For once, this is a case of radical understatement. Not only is it one of the more robust simulation programs available, it is also one of the few such programs that allows the user to create their own operating scripts for use within the basic application (visit the User's Manual as well as the Documentation Page to see for yourself how easy this can be).

If you aren't into writing your own scripts, Celestia is still a very well-designed package. It lets you visit computer-generated versions of every major structure in our solar system, our home galaxy, and even further out into space. On top of all that, it has additional (although optional) educational modules that can be downloaded from its addon pages that will keep your child fascinated for hours on end.

A word of warning: although the basic Celestia installation is easily manageable by even outdated operating systems, you will have to resist the temptation to download and install even more detailed images of planets, their moons, and other astronomical objects. If you aren't careful, you could find yourself with several Gigabytes of extra files! To get an idea of what you could add to the basic installation, take a look at Celestia's screenshots page or the HUGE (meaning Gigabytes of material) addons pages .

You can download the Celestia base program installer from this web page . As is the case with Stellarium, Celestia packages are available for Windows, Linux, and Mac OSX.

To summarize, this posting has presented two excellent software packages that will be of interest to amateur astronomers of all ages and experience levels. In my next post I'll talk about free software for the entire family.