1. What exactly is TerraVista?

It is simply an application which shows you where on earth it is currently day and where it is night. And it does so in graphically pleasing way by drawing even the night side (though that can be turned off). Additionally, new versions (>=0.4) have support for real-time cloud covers downloaded from the internet.

2. Oh, I see. So what is it useful for?

Well, it may not be strictly useful, but I find it interesting nonetheless. It also gives me a visual representation of how night is approaching which in turn gives me a different idea of (day)time. Additionally, it is also a nice desktop decoration.
And with the real-time clouds (TerraVista >=0.4) if also gives you an idea of the weather in various places around the world.

3. Fair enough. But a new cloud map every 3 hours is hardly "real-time", don't you think?

Well, considering that these are satellite images which have to be downloaded from a satellite, processed, distributed to a server, stitched together and distributed again, I suppose this is a close to real-time as you can get.
But you are right, in the strict sense of the word it is not real-time, but rather "fairly current" or something like that.

4. Ok. But is it accurate?

That is a difficult one to answer. I literally searched for hours to find the appropriate equations to calculate the position of the sun at any given time. While I found several algorithms which seem to give more or less accurate results (compared to looking outside the window) I have no means to reliably verify them.
Remember: This application is first and foremost intended to look pretty. Do not use it as a reference of any kind! (this warning is intended especially if you are using real-time clouds).

5. Does it consume a lot of resources when running?

TerraVista is a relatively simple application and consumes not that much. It typically uses around 15-30MB of RAM (it varies) and a relatively small amount of CPU time every 120 seconds (unless you are spinning the globe which takes more CPU time).
If real-time clouds are enabled then the memory consumption might be slightly higher. I tried really hard to make sure that there are no memory leaks, but you never know.

6. What are the system requirements?

The application is compiled as a universal binary which means that it runs both on PowerPC and Intel macs. The OS version required is Mac OS X 10.3.9 for PPC macs and Mac OS X 10.4.4 for Intel macs.
If you want hardware acceleration you need a reasonably recent graphics card. "Reasonably" menas that hardware acceleration is already supported on a Powerbook G4 from 2000.

7. Why is version 0.3 of TerraVista so much bigger than previous versions?

Version 0.3 of TerraVista includes high-resolution textures which make the earth look much better. In total there are three sets of textures (low resolution, high resolution and textures used with hardware acceleration) which make up around three quarters of the whole application size.

8. Why is version 0.4 of TerraVista again so much bigger than previous versions?

Version 0.4 of TerraVista includes seasonal textures. This means that the appearance of the earth changes with the season, as it should. This is only visible when using real-time clouds.

9. Help! Your application is broken! There are some big and ugly defects on the cloud map!

Well, there is not much I can do about that because TerraVista just downloads the cloud map from the internet (from here to be precise). If TerraVista shows a defect in the cloud map then that defect is already present in the image file downloaded from the internet.
Ususally this sorts itself out at the next iteration of the cloud map (every 3 hours). Sometimes it also happens that one of the mirrors has a corrupt image. In that case you can open the preferences and click on "Delete Cloud Cache". TerraVista will then reload the cloud image but there is no guarantee that the defect will disappear.

10. Your application crashed! (not really a question, I know)

I am really sorry about that. But if you send me the crash report attached to a ticket I will have a look at it (provided I find the time to do it, of course).

11. How do I uninstall TerraVista?

Because TerraVista is an application package you can just trash the TerraVista.app. If you want to be really thorough you can also trash the preferences file in ∼/Library/Preferences/ch.ione.TerraVista.
If you used real-time clouds then the last cloud image will be stored under ∼/Library/Application Support/TerraVista. You can delete that folder without problems.

12. What about this automatic version check? What information is transmitted there?

Terravista will just download a text file from this server (version.txt to be precise) and then compare the received version number with the one the user is running.
The request is done using a Cocoa function, but all that is visible in the server log is the IP address and a user string in the form "CFNetwork/129.20" but that's all. I did not check, but I probably could deduce the Mac OS version from that string, but if you actually visit my site with a web browser your web browser sends a lot more information. Anyway, if you feel uncomfortable with this, the version check is deactivated by default.

13. What do I do if my question is not answered in the FAQ?

You can always send me a message here. I will try to answer them but please understand that I might be short on time and unable to answer immediately.