Thursday, May 31, 2012

Google Ghost Planes

A few of you, if you poke around in Google Maps or Google Earth enough, may have stumbled across ghost planes, or sometimes called rainbow planes. These are captured by satellite imagery, where the satellite is scanning the earth just as a plane passes underneath. There are many speculations on what causes the neat effect, all quite technical, but none appear to be from authoritative sources who've actually designed the satellite cameras.

There happens to be one of these ghost planes on a mountain I visit frequently, Pack Monadnock. I've known about it for some time, but never really looked into it until just now. Here's is a close-up of the plane. It may be a DC9, hard to tell. Satellites in low earth orbit whiz by at thousands of miles per hour, while jets cruise hundreds of miles per hour. The camera likely builds the image one color at a time and compensates for it's speed relative to the surface of the Earth, but not a plane traveling fast relative to the Earth. Thus the colors become mis-aligned.

Here's a view in Google Earth of where the plane falls above Pack Monadnock. Look near the summit.  This link will bring you to it in Google Maps.

Sunday I plan to race up Pack Monadnock on foot. It is a 10 mile race and net gains about 2000ft with a little more total climbing. I've yet to run 10 miles, so this ought to be interesting. At least the weather is expected to be cool, if not wet.

No comments: