Where is M13? is a planetarium application that allows users to view details about distant objects in the sky, covering a very large number of items ranging from stars to other galaxies. There are not many apps that can do this, so most of the shortcomings could be forgotten.
One of the perks of the Linux platform is that applications falling in the "planetarium application" category are mostly free. As usual, there are a few exceptions to the rule, but those available are usually very good. The jury is still out for Where is M13?, but its problems have nothing to do with the functionality of the app.
Linux users have been used to seeing apps like Celestia or Stellarium added to various repositories or distros, but there are a few others that don't get mentioned too often, despite the fact that they indeed provide some interesting features. Where is M13? is described as a three-dimensional galactic atlas, and who does't want to have one of those? There is a caveat though, this is not exactly an application for beginners, although it's not all that difficult to understand or use.
Installation
You won't find Where is M13? in the regular repositories, but it's easy to understand why. This is an application that is built in Java and that needs Java to run. There is no source package and it won't be integrated anywhere by default, no matter how good it might prove.
That being said, we have uttered the word Java. It's a requirement for this app and there is no way around it. The good news (if you can call it that) is that it will work with the OpenJDK, which is the freeware version. This can be found in repositories, so getting it shouldn't be a problem. We tested the application in Ubuntu 14.10 (Utopic Unicorn) and it runs without any issues.
You need to open Ubuntu Software Center and look for OpenJDK. We used the OpenJDK 7 and the app didn't seem to mind, but we can't say for certain that it will also work with OpenJDK 8. In any case, once Java has been installed, just unzip the archive and run the binary. Don't forget that it needs to be set at "executable," otherwise it won't start.
Usage and features
First of all, we need to clear up the name of the application. M13 is in fact a globular cluster of stars in the Milky Way galaxy, comprising about 300,000 stars. Back in the 1970s, an experiment was carried out from Arecibo, a famous radio telescope. Details about humans, DNA, our position in the galaxy, and a few other "minor" details have been sent directly towards M13, which is at a distance of about 25,000 light years. The problem is that the message will never reach M13 because by the time it arrives at that location, the globular cluster would have already moved.
The users will see a fairly simple and straightforward interface that has details about our position in the Milky Way galaxy and about M13. Users can search pretty much any of the known objects in order to find its relation with Earth and the Milky Way. For the more advanced users, a number of important details are provided, which would make it easy to find them in the sky with a telescope.
The application has just two views, one with our galaxy in 2D and one with the night sky, with all the stars and constellations. When used with the second view, placing the objects in context is much easier. The application uses a number of important sources, like the Messier catalog and a few others.