Last week, I posted a picture taken by International Space Station astronaut Ron Garan, showing city lights at night. I was curious about what the cities were, and initially had a hard time figuring it out. But, using various tools -- Wolfram Alpha to get the ISS position at the time the photo was taken, an atlas, and a rough direction and scale using the visibility of Orion's belt in the picture -- I took a stab at which cities were which. A followup on that post is in order. A lot of people left comments on the post, and some went through similar sleuthing exercises as I did. Quite a few agree with my assessment: the city in the center of the picture is Warsaw, Poland. Berlin is on the horizon, and other cities are as I determined. I used an old-fashioned atlas to find the cities because I couldn't find a good piece of software to do it. But then I had a facepalmy moment when several people suggested Google Earth! I got a new computer when my Mac died a little while ago, and never installed GE on it. So I downloaded and started fiddling with it, and sure enough the cities do seem to match. If you're curious, go to latitude 50.56 North, longitude 38.23 East, zoom out to an eye altitude of about 221 miles, and rotate the picture so you're facing west. At this point, you'll see a big city centered in the frame that turns out to be Kiev, Ukraine. That threw me for a second, but I remembered that given Orion's size in the ISS photo in question, it's clear the picture is zoomed in a bit. Kiev is off the bottom of the frame. Also, in Google Earth, you can overlay the landscape with a NASA picture of cities at night (in Layers, go to Gallery then NASA then Cities at Night). Zoom in so that Warsaw is centered, and the other cities do indeed appear to line up with my initial guess. So hey, I was right! Richard Drumm, an astronomer who lives in my old stomping grounds in Virginia, kindly annotated an image to show what's what. You can find more in the comments of the original post. And I'm honored to have discovered that Ron Garan, the astronaut who took the picture, tweeted about my post as well! All in all, this was a fun and interesting exercise. It gave me an appreciation for what cartographers do, and also how hard it must be for astronauts to figure out where they are over the Earth. Imagine waking up, looking outside your window, and having no clue at all even what part of the Earth you're seeing! Before teh internetz, I used to spend a lot of time trying to do something like this when I was identifying stars in photographs. When I first looked at Ron's picture I figured it would be easier looking down, but I was wrong. It also was rewarding in a more literal sense, in that I got to find Google Earth all over again, and see that Wolfram Alpha is a pretty useful site. Next time I have a weird question, I'll have to try there first. And, of course, the most important lesson here is that playing is fun, even when it's nerdy and maybe seems at first like a time sink. In a lot of cases, playing leads to learning, and there's always room for that... and there's always much, much more to learn.