Lowell Observatory is an astronomical research institution located in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, by Bostonian Percival Lowell, a businessman and philanthropist with a lifelong interest in astronomy.
In 1896, using a 24-inch refractor telescope at the observatory, Lowell and William H. Pickering discovered Pluto (originally known as “Planet X”), though they did not realize it at the time. This started a heated scientific debate that lasted for decades about whether or not Pluto should be considered a planet; eventually it was classified as a dwarf planet in 2006. The observatory also played an important role in detecting evidence of dark matter and dark energy.
The main telescope at Lowell Observatory is the Discovery Channel Telescope (DCT), which is one of the world’s largest visible-light telescopes. The DCT is a 4.3 meter aperture telephoto lens designed to work in visible light only; it began operations in 2012. Other notable telescopes at the observatory include the Perkins Telescope (the second largest refractor telescope in North America), the Mars Hill Radio Telescope Array (one of only two radio interferometers on Earth capable of imaging extrasolar planets), and the John CoughlinTelescope—the largest binocular telescope in North America.
The staff and researchers at Lowell Observatory are international leaders in many fields of astronomy, including planetary science, cosmology, stellar evolution and astrophysics, solar system dynamics, exoplanet discovery and characterization, asteroid deflection strategies for planetary defense against impactors, development of innovative astronomical instrumentation, public outreach through education programs and public events such as star parties .