Lowell Astronomical Observatory, Flagstaff, Arizona

One of the oldest observatories in the United States, Lowell Observatory was founded in 1894 by astronomer Percival Lowell. Located in Flagstaff, Arizona, at an elevation of about 7,200 feet, the observatory has played a major role in planetary astronomy and the history of modern astrophysics.

The observatory is most famous for the discovery of Pluto in 1930 by Clyde Tombaugh using the 13-inch astrograph telescope — which remains preserved inside its original dome.

Lowell Astronomical Observatory, Flagstaff, Arizona

The Slipher Rotunda Museum welcomes visitors and showcases the observatory’s scientific legacy.

Lowell Observatory -  Entrance Gate

Decorative metal entrance gate featuring astronomical motifs.

Lowell Observatory - Cat Sculpture

Cat sculpture inspired by celestial themes and Lowell’s planetary studies.

Lowell Observatory - Old Telescope

An old telescope displayed outdoors on observatory grounds.

Lowell Observatory - Pluto Telescope - 13-inch Astrograph

The famous 13-inch astrograph used for the discovery of Pluto.

Lowell Observatory Spectrograph

Historic spectrograph demonstrating early astronomical instrumentation.

Lowell Observatory Art

Art inspired by the observatory’s scientists and telescopes.

Welcome to Lowell Observatory

Lowell Observatory Today Program

Lowell Observatory Elementary and Middle School classes

Lowell Observatory SunDial

Lowell Observatory Saturn Lamp

Lowell Observatory Old  Car

Lowell Observatory Sculpture

Lowell Observatory Store

Lowell Observatory Store 2

Lowell Observatory Store 3

Lowell Observatory Electrical Calculator  Millionaire

Lowell Observatory beautifully combines scientific discovery, education, and public outreach. Walking through its historic domes and museum exhibits is like stepping back into the early days of planetary exploration — when careful photographic plates and patient sky surveys revealed new worlds.

Scientific Tools of Another Era

Two small details inside Lowell Observatory stood out as especially memorable. Inside the dome of the 13-inch astrograph — the very telescope used to discover Pluto — a protective glove remains mounted near the instrument. In the era of glass photographic plates, astronomers handled delicate plates by hand in cold, dark domes. The glove is a quiet reminder that planetary discovery once depended entirely on careful human observation.

Equally fascinating was the mechanical “Millionaire” calculator displayed in the museum. Long before electronic computers, astronomers relied on such devices to compute orbital positions and perform precise multiplications required for celestial mechanics. These machines formed the computational foundation of early 20th-century astronomy.

Together, the telescope, the glove, and the mechanical calculator illustrate how discovery was achieved through patience, mathematics, and meticulous manual work — a striking contrast to today’s digital astrophysics.

Other Observatory Visits

• Arecibo Observatory — Puerto Rico
  Formerly home to one of the world’s largest radio telescopes, pioneering planetary radar and radio astronomy research.
• Mauna Kea Observatories — Big Island, Hawaii
  World-class optical and infrared telescopes located above the clouds at 13,796 feet on Mauna Kea.
• Karl G. Jansky Very Large Array (VLA) — New Mexico
  A radio interferometer of 27 movable antennas studying the universe at radio wavelengths.
• Custer Institute & Observatory — Long Island, New York
  One of the oldest public observatories in the United States, dedicated to education and amateur astronomy.
• Sky’s The Limit Observatory — Joshua Tree National Park
  A public observatory operating under exceptionally dark desert skies, supporting outreach and astrophotography.