Celestia/Why Celestia

Why would anyone want to use Celestia?

 * Celestia is free. There are no charges or fees of any kind ever, and everything, including the source code, is open source, meaning that every part of it can be scrutinized, modified, and built on your own.


 * You can explore the universe. Celestia allows you to travel throughout the solar system, stars, and galaxies in three dimensions. It shows the objects as they are in real time. You can go forward or back thousands of years as it can predict the trajectory of many different objects, or slow down time to a crawl. You can accurately view positions of objects from the Earth's position, or leave its confines should you wish.


 * It's easy to use. You can easily explore anything from the scale of tiny asteroids to massive galaxies with simple controls and a simple interface.


 * It's expansive. The default version of Celestia contains over 100,000 stars, 10,000 galaxies, the Solar System and its planets, moons, and dozens of smaller bodies.


 * It's expandable. If Celestia doesn't have what you want to see, you can easily download and install hundreds of different add-ons created by the community, covering everything from high-resolution textures to new stars and planets, and even fictional systems from sci-fi franchises.


 * It can be educational. Many people, such as Frank Gregorio, have made comprehensive lesson plans for educating and entertaining curious minds.


 * You can customize it however you want. Celestia easily allows you to build your own worlds and creations, making it useful for everyone from artists to astronomers.

Why not use some other program?
Free and open source:
 * Gaia Sky
 * Stellarium
 * OpenSpace
 * WorldWide Telescope

Free and closed source:
 * Orbiter
 * NASA's Eyes

Commercial:
 * SpaceEngine
 * Universe Sandbox
 * Starry Night

All of the above software titles are useful in their own right. However, Celestia is open-source, meaning it is open to all kinds of collaboration and improvement from anybody, and it allows thorough journeys to the planets, their moons, the stars, asteroids, comets, and galaxies — all in one place, and while being quite light on processing power. These visits are up-close and personal and in vivid detail with exceptional graphics and animations. If it's missing in Celestia, you can install any of hundreds of add-ons that include spacecraft, nebulae, and others, and see what they look(ed) like in space.

What can't Celestia do?

 * Telescope control


 * 180 degree field of view


 * Sound (prior to recent builds of 1.7.0)


 * 3D stereoscopic or anaglyph viewing