Software I've found that I think is particularly useful or interesting.

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04/07/2003: Celestia [>> Go]

    Celestia is a real-time, three-dimensional simulation of the Milky Way galaxy (and beyond). Think of it as a 3-D planetarium that you can fly around in. Celestia simulates both space and time, so you can not only pick a location in the galaxy to observe, you can also pick a time in which to observe it (within reason; you can't go back to the Big Bang and watch the universe expand). For example, the picture to the right shows Halley's Comet's next terrestrial flyby in 2061 on the day it will be closest to Earth (at least as Celestia calculates it) - October 3. The red line is Halley's Comet's orbit; the blue lines are the orbits of Mercury, Venus, Earth, and Mars.

    Celestia has a lot of visualization options that you can turn on or off to control what you see. The screenshot to the right has orbits, planetary labels, and asteroid labels turned on (those are the brown words toward the bottom of the picture). My favorite is to turn on constellations, which draws connect-the-dot lines on all the constellations to help you see where they are. You can even watch eclipses (solar or lunar) if you can find them; a nice feature is a built-in eclipse calculator that can find the exact date and location of an eclipse and then take you there to watch it happen.

    Navigation through the galaxy can be accomplished in many ways. You can "fly" around using a joystick or basic keyboard controls (your speed is basically unlimited; you can slow down to 1 km/sec or zoom across the galaxy at thousands of light years per second). You can pick a planet, star, or other object by clicking on it, picking it from a list, or typing in its name, and then flying directly to it. You can orbit celestial bodies, follow them in their orbits, or just sit in one place and watch the universe go by. Special keyboard commands let you quickly jump from planet to planet within our solar system. You can even create scripts to take the viewer on a tour of locations or times you think are interesting, or take snapshots or make video clips of your travels.

    Celestia has a community of users who are fairly active in creating new data for the program, from updated asteroid and comet information to new maps of the planets and moons. You can even create your own solar system or galaxy by creating a new set of planet or star data.

    While I find Celestia very pretty to look at and interesting to use, I have no idea what to do with it. One teacher has created a lesson plan based around Celestia, which takes students on a tour of the solar system. I also have no idea how accurate it is, though one test I did in Celestia was corroborated with external data (finding the next time when Mars will be at its closest point to Earth; turns out it's this August, 2003, and Mars will be the closest it has been in more than 70000 years). So I don't really know what to use Celestia for, but I'm going to keep it around in case I think of something.

©2019 Tyler Chambers