From Heaven to Earth (Synopsis)

If you want to know where you are on Earth, you use a GPS, you use other terrestrial landmarks to help determine your location, or you use some well-known objects in the sky.

Image credit: still by Fraser Gunn, additions by Ethan Siegel.
Image credit: still by Fraser Gunn, additions by Ethan Siegel.

This will get you latitude easily, but how about longitude? While there are some tricky things you can do to help yourself out, one of the most commonly used techniques for centuries — surprisingly — was using the moons of another world: Jupiter!

Image credit: Robert J. Modic, over a mere 10-minute timespan! Image was processed down from 3.2 MB to a mere 274 kb by Cleon Teunissen.
Image credit: Robert J. Modic, over a mere 10-minute timespan! Image was processed down from 3.2 MB to a mere 274 kb by Cleon Teunissen.

Come check out this unusual and fun use of Jupiter’s moons, courtesy of Brian Koberlein, over at Medium!