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Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965.[2][3] In 2011, the Observatory was named one of "The World's 100 Most Important Places" by TIME. It was at the Lowell Observatory that the dwarf planet Pluto was discovered in 1930 by Clyde Tombaugh.

Lowell Observatory
Clark dome.jpg
The Clark Telescope Dome on Mars Hill
Organization Private institution
Observatory code 690
Location Flagstaff, Arizona
Coordinates 35°12′10″N 111°39′52″W / 35.20278°N 111.66444°W / 35.20278; -111.66444Coordinates: 35°12′10″N 111°39′52″W / 35.20278°N 111.66444°W / 35.20278; -111.66444
Altitude 2,210 m (7,250 ft)
Established 1894
Discovery Channel Telescope 4.28 m (169 in) telescope (located at Happy Jack, Arizona)
Perkins Telescope 180 cm (72 in) cassegrain telescope (located at Anderson Mesa)
John S. Hall Telescope 110 cm (42 in) Ritchey-Chretien telescope (located at Anderson Mesa)
Unnamed telescope 79 cm (31 in) reflecting telescope (located at Anderson Mesa)
LONEOS Schmidt Telescope 64 cm (25 in) catadioptric (located at Anderson Mesa)
24-inch Clark Telescope 61 cm (24 in) Alvan Clark refractor
Unnamed telescope 53 cm (21 in) reflecting telescope
Unnamed telescope 46 cm (18 in) astrograph
John Vickers McAllister Telescope 41 cm (16 in) Boller and Chivens cassegrain telescope
Abbot L. Lowell Astrograph (Pluto Discovery Telescope) 33 cm (13 in) astrograph
Planet Search Survey Telescope (located at Anderson Mesa)
Navy Precision Optical Interferometer

six-aperture astronomical interferometer with baselines up to 437 m (1,434 ft) (located at Anderson Mesa, operated in partnership with the USNO (through NOFS) and the NRL)

Lowell Observatory
The Slipher Rotunda Museum at Lowell Observatory
Lowell Observatory is located in Arizona
Lowell Observatory
Lowell Observatory is located in the US
Lowell Observatory
Built 1894
MPS Flagstaff MRA (AD)
NRHP reference # 66000172
Significant dates
Added to NRHP October 15, 1966[1]
Designated NHL December 21, 1965[2]
Lowell Observatory is located in the US
Lowell Observatory
Location of Lowell Observatory
Commons page Related media on Wikimedia Commons

The Observatory's original 61-centimeter (24-inch) Alvan Clark & Sons Telescope is still in use today for public education. Lowell Observatory hosts 85,000 visitors per year at their Steele Visitors Center, who take guided daytime tours and view various wonders of the night sky through the Clark Telescope and other telescopes. It was founded by astronomer Percival Lowell of Boston's well-known Lowell family and is overseen by a sole trustee, a position historically handed down through the family. The first trustee was Lowell's third cousin Guy Lowell (1916–1927). Percival's nephew Roger Putnam served from 1927–1967, followed by Roger's son Michael (1967–1987), Michael's brother William Lowell Putnam III (1987–2013), and current trustee W. Lowell Putnam.

The observatory operates several telescopes at three locations in the Flagstaff area. The main facility, located on Mars Hill just west of downtown Flagstaff, houses the original 61-centimeter (24-inch) Clark Refracting Telescope, although its role today is as a public education tool and not research. The telescope, built in 1896 for $20,000, was assembled in Boston by Alvan Clark & Sons and then shipped by train to Flagstaff. Also located on the Mars Hill campus is the 33-centimeter (13-inch) Pluto Discovery Telescope, used by Clyde Tombaugh in 1930 to discover the dwarf planet Pluto.

Lowell Observatory currently operates four research telescopes at its Anderson Mesa dark sky site, located 20 km (12 mi) southeast of Flagstaff, including the 180-centimeter (72-inch) Perkins Telescope (in partnership with Boston University) and the 110-centimeter (42-inch) John S. Hall Telescope. Lowell is a partner with the United States Naval Observatory and Naval Research Laboratory in the Navy Precision Optical Interferometer (NPOI) also located at that site. The Observatory also operates smaller research telescopes at its historic site on Mars Hill and in Australia and Chile.

Past Anderson Mesa, on the peak of Happy Jack, Lowell Observatory has also built and is commissioning the 4.28-meter (169-inch) Discovery Channel Telescope in partnership with Discovery Communications, Inc.


History (see discoveries below)Edit

Aside from the wide array of research and discoveries listed below, one science program carried out at the Observatory was the measurement of the variability of solar irradiance.[4] When Harold L. Johnson took over as the director in 1952, the stated objective became to focus on light from the Sun reflecting from Uranus and Neptune.[4] In 1953, the current 53 cm (21-inch) telescope was erected.[4] Beginning in 1954, this telescope began monitoring the brightness of these two planets, and comparing these measurements with a reference set of sunlike stars.[4]

Discovery Channel Telescope (DCT)Edit

Rotunda building

Lowell Observatory is building a major new reflecting telescope in partnership with Discovery Communications, located near Happy Jack, Arizona. This Discovery Channel Telescope (DCT), located within the Mogollon Rim Ranger District of the Coconino National Forest, is expected to be the fifth-largest telescope in the contiguous United States, and it will enable the astronomers of Lowell Observatory to enter new research areas deeper into outer space.

The DCT and the research carried out there will be the focus of ongoing informative and educational television programs about astronomy, the sciences, and technology to be telecast on the Discovery channels. The primary mirror of the Discovery Channel Telescope will be 4.28 m (169 in) in diameter. It will be supposedly notable for its uncommon meniscus design for such a large mirror. This mirror was ground and polished into its parabolic shape at the Optical Fabrication and Engineering Facility of the College of Optical Sciences of the University of Arizona (in Tucson, Arizona).

Current researchEdit

Lowell Observatory's astronomers conduct research on a wide range of solar system and astrophysical topics using ground-based, airborne, and space-based telescopes. Among the many current programs are a search for near-Earth asteroids, a survey of the Kuiper Belt beyond Neptune, a search for extrasolar planets, a decades-long study of the brightness stability of the sun, and a variety of investigations of star formation and other processes in distant galaxies. In addition, the Observatory staff designs and builds custom instrumentation for use on Lowell's telescopes and elsewhere. For example, Lowell staff built a sophisticated high-speed camera for use on the Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is a joint project of the United States and German space agencies and consists of a 2.5-meter (8.2-foot) telescope on board a Boeing 747 SP.

Notable discoveriesEdit

See alsoEdit


  1. ^ National Park Service (2007-01-23). "National Register Information System". National Register of Historic Places. National Park Service. 
  2. ^ a b "Lowell Observatory". National Historic Landmark summary listing. National Park Service. Retrieved September 27, 2007. 
  3. ^ Marilynn Larew (October 31, 1977). "National Register of Historic Places Inventory-Nomination: Lowell Observatory" (PDF). National Park Service. Retrieved May 5, 2009.  and Accompanying six photos, exterior, from 1964 and 1976
  4. ^ a b c d Wotkyns, Steele (2006). "Lowell Observatory's 21-inch Telescope Delivering Long-Term Results". Reflector. the Astronomical League. LVIII (2): 16. 
  5. ^ Schleicher, David G.; Millis, Robert L.; Thompson, Don T.; Birch, Peter V.; Martin, Ralph; et al. (1990). "Periodic variations in the activity of Comet P/Halley during the 1985/1986 apparition". Astronomical Journal. 100: 896–912. Bibcode:1990AJ....100..896S. doi:10.1086/115570. 


  • Strauss D. (1994). "Lowell, Percival, Pickering, W.H. and the founding of the Lowell Observatory". Annals of Science. 51 (1): 37–58. doi:10.1080/00033799400200121. 
  • David Strauss, Percival Lowell: The Culture and Science of a Boston Brahmin (Cambridge: Harvard University Press, 2001)
  • William Graves Hoyt, Lowell and Mars (Tucson: University of Arizona Press, 1976)
  • William Lowell Putnam, The Explorers of Mars Hill: A Centennial History of Lowell Observatory, 1894-1994 (New Hampshire: Phoenix Publishing, 1994)

External linksEdit

Historic American Buildings Survey (photographic survey)Edit