Rick beat me to the punch about the light-pollution question from Wile E. Coyote-ish Super Genius Marilyn vos Savant on Sunday. I've written to her in the past about questions that I thought she answered in an incomplete manner in my view, missing the point of the query. Both times she replied saying that she believed what was published was sufficient. Fine. I guess you can't give the whole truth when half of the column space is left to answering riddles and word/number puzzles. Her "silly question" columns are the worst. Other than her essentially publicly rubbing people's noses in their own ignorance, usually there are a few questions that could actually be answered very simply (Sheesh, even I know why manhole covers are round. It's a one sentence answer see below.)Anyway, I digress somewhat. I'm still going to talk a little about light pollution though.
I'm surprised I haven't heard more about the latest from Google Earth. As of two weeks ago, the software now includes layers of data from NASA. Look under the "Featured Content" section of the Primary Database menu.
Right now, there are three interesting choices: Astronaut Photography of Earth, Satellite Imagery, and Earth City Lights. The astronaut photos appear as NASA's "meatball" logos scattered across the planet. Each symbol denotes a picture with description. Click on one and a photo and detailed caption will pop up. You can see an example of a snowy Baltimore by clicking on the image above for a larger version of the Google Earth screen.
The Earth at Night view itself isn't new. This shining example of the effects of light pollution has been on posters for years. Although the layer isn't as detailed as other data layers, it's nevertheless fascinating to have it incorporated into Google Earth. You can easily identify every bright dot and trace highways across the continent. The regions of Earth-glow are pretty, but also sad. All that wasted energy.
I'm planning on discussing these NASA layers in the Astronomy Online column in the November issue of Sky & Telescope. In the meantime, you can get some details from the Google Lat Long Blog.
(So why, pray tell, are manhole covers round? Because it's the only shape that won't allow the cover to fall into the hole. Is that so silly?)