A potential new dwarf planet has been discovered in the outer reaches of the solar system, and its existence poses the ...

FLAGSTAFF – Clyde Tombaugh sat in the Orpheum Theater that fateful night in February 1930, waiting for clouds to pass before the 24-year-old astronomer could return to Lowell Observatory to ...

Beyond the vintage diners and roadside kitsch, Route 66 passes stunning natural attractions from Missouri caves to Arizona ...

Founded in 1894, this historic site is where Clyde Tombaugh discovered Pluto, and astronomers continue to unlock the secrets of deep space. Tour the historic telescopes, attend a live sky show ...

It's the only planet discovered in the United States — done right here in Arizona by a high school graduate from Kansas named Clyde Tombaugh, who was working at Lowell Observatory in Flagstaff.

One Pluto year equals 248 Earth years. At 1473 miles in diameter—about half the width of the United States—Pluto is the ...

FLAGSTAFF — At Lowell Observatory, where Pluto was discovered in 1930, a crowd waited anxiously Tuesday afternoon for the “beep” that would signal New Horizons had successfully completed its ...

Lowell Observatory is the historic site where Pluto was discovered in 1930 by Clyde Tombaugh. The site was founded by mathematician, businessman and diplomat Percival Lowell in the late 1800s.

Daytime visitors can enjoy a quick peek at the sun (daily at 12:30 p.m.) or stroll down the Pluto Walk to see the 13-inch photographic telescope that Clyde Tombaugh used in 1930 to discover ...