Where is Io is my first foray into Android development. I got the idea after a Mid Hudson Astronomy post meeting observing session of Saturn. There was a little discussion about which moon we were looking at, and it occurred to me that having that information in your pocket would be a great thing.
I started with Jupiter because you can see all 4 moons with binoculars, making it an accessible Astronomy target for a wide range of people. I added a number of fun facts about the moons as well, because getting a sense of what's really up there helps people connect to the wonders in our solar system. Here are a few screen shots from the application:
Where is Io is currently available in the Android Market for the low low price of free. You can directly get it via
Upcoming Ideas / Features
I've got a lot of other ideas for this application, many of which will get implemented over the next couple of months:
- Display of day / night areas in the timeline
- Configurable time range (it's currently fixed at 96 hours)
- Events (like occultations and shadows)
- A zoom view of Jupiter with the events.
- Saturnian System support
Over all simplicity and beauty are what I'm going for. Keeping the interface clean and crisp.
- v2.1 - Make native code a fat binary so it's faster on most phones; Make Diarama less flakey.
- v2.0 - Install to SD card (thanks Keith); New Diarama front screen showing current planets that are up; Jovian spirals go over under correctly; Rise and Set times for all planets.
- v1.3 - Refactoring for responsiveness. Time markers.
- v1.2 - Minor spelling fix
- v1.1 - Initial Release
Thanks to Keith McGerald for the install to SD changes.
Thanks to Sean Swehla for helping me relearn my linear algebra. It has been a decade since I'd done that kind of math, and a few mornings with us playing on his whiteboard got me over the hump and unlocked that part of my brain again.
Thanks to Johannes Gajdosik for his porting of various fortran models for solar system motions to C, and releasing that code under a BSD license. Proper credit is given to him in the application About window as well.
Feedback / Support
Due to some increased additional developer interest, I've created the Where is Io mailing list. If you are interested in futures of Where is Io, or want to get into the development discussion sign up for the list. Keith and I are current hammering out some of the more advanced futures for the application, and interesting ideas that could go into it.
Please feel free to post a comment here. I've tested the application on my HTC Hero (previously) and HTC EVO on real hardware and in the emulator. Reports on success or issues on other hardware platforms would be appreciated. Issues can be tracked on github.