Kosmorro is described as 'A software to calculate the astronomical ephemerides' and is an app in the Education & Reference category. There are three alternatives to Kosmorro for Linux, Windows, Mac, PortableApps.com and Wine. The best alternative is Stellarium, which is both free and Open Source. Other great apps like Kosmorro are Celestia (Free, Open Source) and WinStars (Freemium).
Stellarium is a free open source planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. It is being used in planetarium projectors. Just set your coordinates and go.
Celestia is an application for real-time 3D visualization of space, with a detailed model of the solar system, over 100,000 stars, more than 10,000 galaxies, and an extension mechanism for adding more objects.
WinStars uses the latest 3D technology to show the objects of our solar system in a realistic manner. Thus, it is possible to move from one planet to another, to follow a space probe on its long voyage or to observe a celestial event from a place to which you could never go.