Celestia is a fun app for anyone interested in astronomy. When you first load it you will be brought to a view of the Earth from Space. This view is a real-time simulation and you can change your point of view by dragging your mouse around. The initial time you see might be in the past (it was 2002 for me), but one of the buttons on the toolbar can bring you up to the current time.
Right clicking on a visible object in space will bring up details about it along with some options for different actions you can take. I choose the Moon and selected the Goto option. In short order I was on my way with the Moon rapidly filling up my screen. After right-clicking on the Moon again I noticed a menu called Satellites which listed Apollo 11. You can actually sync your orbit with the Apollo 11 space craft and see what it can see. How cool is that! Now I was curious. What does Celestia list as orbiting the earth?
Clicking the Follow the Earth link above the view window sent me back to my starting point and I tried the same steps I did with the Moon. While they obviously don't have a complete list of satellites orbiting the Earth, such notables as the Hubble Space Telescope and the International Space Station are available. This time I choose Hubble and wheeled around to check out what it's seeing right now.
I picked a star at random and ended up choosing Alnair, a class B7 IV star, 101+ light years away, with a luminosity 169 times that of the Sun, and a surface temperature of 13000K. And here I thought Texas in the summer was hot.
Finding a star at random can be interesting, but what if you want to find something specific? The Navigation menu has tools to find specific longitude/latitude coordinates, a Celestial Browser, and even an Eclipse Finder. The Celestial Browser allows you to find a star, planet, or other object by name.
Celestia also makes it simple to turn on and off labels for various celestial bodies as well as what types of objects that you want to see. This includes such notables as constellations and galaxies.
I've only just scratched the surface with Celestia so far, but I found it to be a delightful way to explore our solar system and beyond.