Arizona has been at the forefront of space discoveries and NASA missions.
The state's clear skies and low humidity make the place an ideal site for star gazing, drawing scientists and researchers from around the world.
In 1930, 24-year-old amateur astronomer Clyde Tombaugh famously discovered Pluto while working at Lowell Observatory in Flagstaff. The small planet was controversially downgraded to "dwarf" planet status in 2006 by the International Astronomical Union.
Besides Pluto, the University of Arizona was the first university to lead a mission to Mars in 2008. The unmanned Phoenix Mars Lander was the first to touch down in the Red Planet's icy polar region. Its discoveries drew international attention. The table-size spacecraft helped advance the theory that water once flowed and Mars was once habitable. It's still a mystery, though, whether life ever existed there.
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