If the thought of planets, stars, and galaxies excites you, then you'll want to download these astronomy-based iPad apps.
Strap yourself in and get ready to explore the universe.
There's a reason that Apple included "Star Walk" as part of its demo package when it showcases the iPad at its multiple stores -- it's easily the best one out there. This application comes with an abundance of information, and it can act as your own personal planetarium as you explore the cosmos. Use the Digital Compass and the swath of sky above you will recreated on your device, allowing you to explore any given section of it with a tap on the screen. There's also a nifty Time Machine mode, when you can jump ahead to a future date to see how the stars will look at that point. You can see moon phases in real time, while getting the known facts on most constellations and planets through Wikipedia links. And it's all done through a handy set-up that shows you everything you need to know -- and even some stuff you didn't. "Star Walk" is out of this world.
"SkyVoyager" (Carina Software, $14.99)
While "SkyVoyager" is a more expensive visionary tool than "Star Walk" ever could be, it also brings a pair of additional items that astronomers will think are utterly cool. First off, you can connect the application through Wi-Fi to a computer-controlled telescope, enabling you to look at the stars in real time. Granted, it helps to actually own one of these, but there are a few of you out there who probably have one around the college lab or something. In addition, Time Flow allows you to follow the course of a planet or star system for days, weeks, or even years, but compressed into only a few seconds. The touch display is user-friendly, and some of the images are absolutely dazzling. If you're all about seeing stars, this is a nice complementary buy to go with "Star Walk."
"Emerald Observatory for iPad" (Emerald Sequoia, $.99)
Rather than a full-on exploration program, "Emerald Observatory for iPad" is more like an astronomical clock. Still, for those of you who are into that sort of thing, it does its job dynamically. You can track a number of things with this tool, including the setting and rising of different planets (including the moon and the sun), the Heliocentric orrery of each planet (basically their rotation around the sun), solar and UTC time monitoring, and the ability to find altitude and azimuth for each planet, though you'll need to do them separately. It's a bit technical, and you'll get lost if you don't quite understand astronomy, but some people will find this "Observatory" well worth visiting. Especially for only a dollar.
"Galaxy Collider HD" (Klaus Engel, $1.99)
You remember that song by Powerman 5000 called "When Worlds Collide?" Well, "Galaxy Collider HD" lets you do just that, smashing two galaxies into one another and watching the cataclysm that follows. You do this by simulating the physics of both galaxies, then mushing them together like peanut butter and chocolate and watching the fun unfold. Just for fun, you can also change viewpoints and certain physics for each galaxy to see what would change with each head-on scenario. While a bit unrealistic at times, "Galaxy Collider" is great to get lost in, since you'll probably never see something like this in real life.
"Moon Atlas" (Horsham Online Limited, $5.99)
Suppose you didn't feel like exploring the whole galaxy, and instead just wanted to focus on a specific spot -- like, in this case, the moon. "Moon Atlas" is your program of choice here, as you can scan it using a faithfully recreated 3-D globe of our planet's celestial neighbor. Check out minute details, such as phase, angular sizes and craters, or go looking at the one of 28 spacecraft that landed on the moon for a quick history lesson. It's the next best thing to checking out the real thing on your dad's telescope, and far more interactive.
"Planets" (Dana Peters, free)
Let's say you want a program that's a little less technical and simply lets you take a gander at planets, both from a 2-D and 3-D perspective. Enter "Planets", a free application that's real handy to use, and one that doesn't take up too much space at all -- just under 10 MB. By touching the Globe option, you view 3-D models of each planet, checking out Saturn's rings and the freezing surface of Pluto. You can also check out moon phases and names by using the Visibility option, and whisk your fingers across the screen to see what's around you. Amateur star-seekers and young kids will want to check these "Planets" out.
"Astronomy Picture of the Day" (Concentric Sky, free)
Last but definitely not least, here's an application that everyone will love, newbies and seasoned astrologists alike. "Astronomy Picture of the Day" is just that, a daily highlight showcasing the more wondrous parts of our universe. As you can see above, the images come through crystal clear, looking nothing short of spectacular on the iPad display. And it's not just limited to the current day, either. With full cooperation from NASA, the program allows you to browse through decades of photos, taken through the Hubble. If you find some favorites, you can save them onto your iPad for use as wallpaper or to show your fellow nerds over a lunch period. This one really shows you the wonders of space, and at no charge. Don't miss it.