Virtual Planetariums for the Lazy Explorer

1. Google Earth

   
   
   
   Google Earth is probably the most-well known app on this list. Similar to Google Maps, it allows you to explore the planet. You can view our planet from a world scale, or zoom in close enough to see your own house. Another feature is the terrain, which can be viewed in 3D.
   
   Google Earth can also display 3D buildings, places of interest, country borders, roads, weather and tons more. Add-ons can be downloaded from the website. They range from Air Traffic to Real Time Earthquakes and more. Google Earth also has a function that allows users to view the sky.

2. Celestia

   
   
   Celestia is a program that allows you to browse the universe in three dimensions. From the Earth to the distant reaches of the Milky Way and beyond, you can explore Planets, Moons, Solar Systems, Suns and even a few of the satellites that orbit Earth. What makes it different from other Planetarium software is the fact that you're not confined to the Earth's surface.
   
   Another great feature is that it is expandable. If the 100,000 star and planet catalogue is not big enough for you, they have a huge range of expendables, ranging from Spacecraft and Planets to fictional solar systems and the Death Star. If you love astronomy, you'd be mad to miss this program.

3. Stellarium

   
   
   Stellarium is an Open Source project from SourceForge. It is basically a planetarium, and you can look at the sky at any time, date or year, and see where the stars and planets are going to be. All this can be viewed from a variety of different landscapes, and you can zoom in to see planets in more detail.

Other Programs to Try

NASA World Wind

Orbiter Space Flight Simulator

Other Astronomical Software