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Stars
GPS satellites tell us where we are, but what tells them where they are?
By Jeff Salton
18:00 November 1, 2009 PST
Global Positioning System (GPS) devices have permeated society to the point where millions of us rely on them daily for directions, locations and traffic avoidance (if only they could tell me where I left my car keys). GPS satellites send signals to a receiver in your handheld or car-based GPS navigator, which calculates your position on the planet based on the location of the satellites and your distance from them. The distance is determined by how long it took the signals from various satellites to reach your receiver. But have you ever thought what tells the GPS satellites where they are in the first place? Read More
Swift snaps our best-ever ultraviolet image of neighboring Andromeda Galaxy
By Jeff Salton
18:51 September 20, 2009 PDT
In a galaxy far, far away … about 2.5 million light years, in fact, lie approximately 20,000 hot, young stars and dense clusters that comprise the Andromeda Galaxy. The galaxy, known as M31 in the constellation Andromeda, was recently captured by an ultraviolet optical telescope aboard NASA’s Swift satellite, and delivers the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet. Read More
Terotech
- November 21, 2009 @ 19:38 UTC
