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. In 2011, the Observatory was named one of "The World's 100 Most Important Places" by Time magazine.

History

Founding in 1894

In 1877 the Italian astronomer Giovanni Schiaparelli purported to have discovered a series of Martian canals. Percival Lowell had seen these drawings and was fascinated by the idea of artificial canals in Mars. In the winter of 1893, he devoted to use his wealth and connections to establish an observatory in the US. His wealth stemmed from his connection to the influential Boston Lowell family and his successful career as an investment banker. Lowell hired American astronomer Andrew E. Douglass to find a suitable location for the observatory, and in 1894, they agreed to build it in Flagstaff, Arizona due to its elevation, dark night skies, and proximity to the railroad. The materials for the construction of the observatory were all sourced locally, but the Clark Refracting Telescope was assembled in Boston. Funds for the observatory were provided by Percival Lowell himself, including staff salaries.

Much of the early research was carried out or overseen by Vesto Melvin Slipher. V.M. Slipher began his career at Lowell in 1901 as a temporary observing assistant. He proved his talent quickly, becoming the Assistant Director in 1915, Interim Director in 1916 after Percival Lowell's passing, and full Observatory Director from 1926 to 1954. While initially hired to study the planets, Slipher carried out careful work that laid the groundwork for observational cosmology. This included the discovery of galaxy recession, galaxy rotation, and of the first spectra of a Seyfert galaxy in M77. His data on the radial velocity of 45 galaxies was used by Sir Arthur Eddington in the development of General Relativity and used by Edwin Hubble to explain the expansion of the universe. Slipher was perhaps the best spectrographer of the era. He observed the spectral lines of methane and ammonia in the ice giants, attempted to find water and chlorophyll on Mars, and measured the rotation of Venus and Uranus. Vesto discovered the nature of the Pleiades and ρ Ophiuchi as reflection nebulae, which he considered his greatest contribution to astronomy. He was the first to observe oxygen and nitrogen in Earth's aurorae and took early spectra on supernovae remnants. As director, he oversaw the Trans Neptunian survey that culminated in the discovery of Pluto by Clyde Tombaugh. Vesto Slipher's research and administrative acuity shaped the path of Lowell Observatory for the decades to come.

List of Lowell Observatory directors

  • Percival Lowell: 1894 – 1916
  • Vesto Slipher: 1916 – 1954
  • Albert G. Wilson: 1954 – 1958
  • John S. Hall: 1958 – 1977
  • Arthur Hoag: 1977 – 1989
  • Bob Millis: 1989 – 2009
  • Jeff Hall: 2009 – 2024
  • Amanda Bosh: 2024 – Current

Historical research

Martian canals

Percival Lowell became one of the major proponents of the existence of Martian Canals, which he believed were evidence of life on Mars. Lowell began observing Mars in Flagstaff in 1894 using borrowed instruments. In 1895, he ordered the construction of a new instrument, a 24-inch refractor designed by Alvan Clark and Sons. Over the next decades he built up a body of work including sketches, maps, hand-drawn globes, and eventually photographs taken by Earl C. Slipher. In all his observations, Lowell perceived recurring, linear features that he interpreted to be artificial water canals. Lowell invited guests to view Mars, many of them also saw canals. He published three books on the subject: Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). Percival's views on the subject caused much controversy among professional astronomers and stirred interest among the public. It appears that the canals were natural features that the human eye connects into linear features, such as hilltops and dust-strewn landscapes.

Lowell Observatory was featured in an episode of Carl Sagan's Cosmos series, titled Blue for a Red Planet. The episode begins with early speculations about Mars by Giovanni Schiaparelli and Percival Lowell and progresses to the robotic explorations of the planet.

Several Martian craters are named after Lowell staff, including Lowell, Slipher, Lampland, and Douglass.

The search for Planet X

After the discovery of Neptune in 1846 through mathematical calculation, astronomers speculated about the existence another planet beyond Neptune based on observed perturbations in Uranus' orbit. Percival expressed interest in the problem in his 1903 book, The Solar System, and began an effort to discover this unknown planet, which he dubbed 'Planet X'. Trained as a Harvard mathematician, he began calculations of likely locations of Planet X. Soon, he hired computers to aide in this effort, led by Elizebeth Williams. The first search lasted from 1905 to 1909 using the 24-inch Clark Telescope, with no success. In 1910, the observatory dedicated more resources to the search as a rival astronomer, William Henry Pickering of the Harvard College Observatory, published an orbit and position of a theoretical trans-Neptunian planet. From 1910 to his death in 1916, Percival dedicated much of his time to the search for Planet X. At this time a 5-inch Brashear Lens and 9-inch telescope borrowed from the Swarthmore Observatory were employed. In 1915, he published A Memoir on a Trans-Neptunian Planet, which included his best estimates of the possible locations of Planet X.

thumb|Pluto Dome housing the 13-inch astrograph, built in 1929.

In 1928, Percival's brother and President of Harvard, Abbott Lawerence Lowell, donated $10,000 for the construction of a new instrument to continue the search. This instrument would later be named the Pluto Discovery Astrograph, or Pluto Camera. Observatory Director Vesto Slipher hired Clyde Tombaugh to operate the astrograph and examine the plate photographs using a recently acquired Zeiss Blink Comparator. On 18 February 1930, Tombaugh was examining two plates taken on 23 January and 29 January and discovered Pluto. As a reference set, phometric measures of Sun-like stars were included.

Lunar mapping

In preparation for the Apollo Program, the United States Air Force's Aeronautical Chart and Information Center (ACIC) began mapping the surface of the Moon in 1959. Between 1961 and 1969, the ACIC established offices on Lowell Observatory's campus to make use of the 24-inch Clark Telescope. Dozens of scientists, photographers, and illustrators were involved, with notable contributions by the artist Patricia Bridges. A 20-inch (51 cm) refractor was constructed to accommodate these observers, now called the Apollo Telescope. Dozens of maps were completed, increasing our knowledge of lunar geology and allowing the first Moon landings.

Dark matter

Beginning in 1965, visiting astronomers Vera C. Rubin and Kent Ford of the Department of Terrestrial Magnetism (DTM) used Lowell Observatory's 72-inch Perkins Telescope and the KPNO 84-inch Telescope to investigate the rotation curves of galaxies. Using Kent Ford's spectrometer, Rubin confirmed the existence of dark matter. Their instrument still resides at Lowell Observatory in storage.

Proper motion survey

Working under the direction of Dr. Henry Giclas, observers Robert Burnham Jr. and Norman G. Thomas conducted a Proper Motion Survey using the 13-inch Pluto Discovery Astrograph from 1957 to 1981. This comprehensive survey produced positions, magnitudes, colors, and proper motions for thousands of stars. Burnham and Thomas discovered 5 comets, more than 1,500 asteroids, 9,000 high proper motion stars, 2,000 white dwarf candidates, and thousands of variable stars. Proper Motion Survey data is currently used to study stellar populations and orbits of minor planets. Robert Burnham is best known for his 2,138 page book, Burnham's Celestial Handbook, which remains a staple for amateur astronomers today.

NASA International Planetary Patrol Program

Lowell Observatory participated in the International Planetary Patrol Program from its formation in 1969 until 1990. Lowell scientist William A. Baum coordinated the activities of several observatories to continuously monitor the surface features and climactic changs on Mars, Jupiter, Venus, Saturn's moon Titan, and others. The Great Red Spot of Jupiter and the global dust storm on Mars that lasted from 1971 to 1973 received extensive coverage. Many of the observations conducted at Lowell used the 24-inch Clark Telescope.

The astronomer Ted Bowell directed a search for Near-Earth Objects from 1993 to 2008. The LONEOS team observed more than 5.2 millions asteroids and discovered 22,077 minor planets. Observers included Brian Skiff, Bill Ferris, Mike Van Ness, Shawn Hermann, Jason Sanborn, and others. The search was conducted using a 0.6-meter, f/1.8 Schmidt camera located at the Anderson Mesa Station.

Notable scientists

{| class="wikitable"

|+Notable Lowell Observatory Staff Members Past and Present

!Name

!Years Active at Lowell

!Work

|-

|Vesto Melvin Slipher

|1901 - 1958

|Observatory Director, discovered galaxy recession

|-

|Carl O. Lampland

|1902 - 1951

|Planetary photography

|-

|Earl Carl Slipher

|1906 - 1964

|Planetary Photography, Mars

|-

|Elizabeth Williams

|1905 - 1922

|Calculator for Planet X Search

|-

|Clyde Tombaugh

|1929 - 1945

|Discovered Pluto

|-

|Henry Giclas

|1931 - 1979

|Oversaw Proper Motion Survey

|-

|Harold L. Johnson

|1952 - 1959

|Developed UBV photometric system

|-

|Robert Burnham Jr.

|1958 - 1979

|Observer for Proper Motion Survey

|-

|Otto Franz

|1965 - Emeritus

|Astrometry, Binary Stars

|-

|William A. Baum

|1965 - 1990

|Planetary Patrol Program

|-

|Leonard Martin

|1960s - 1990s

|Martian atmosphere and weather

|-

|Wes Lockwood

|1972 - 2007

|Solar-stellar photometry

|-

|Nat White

|1973 - 2007

|Stellar Occultation, Program Manager NPOI

|-

|Ted Bowell

|1973 - 2011

|Near Earth Object Survey

|-

|Larry Wasserman

|1974 - Current

|Kuiper Belt Objects, Minor Planets, Co-discoverer of Uranus' Rings

|-

|Brian Skiff

|1976 - Current

|Minor Planets, Stellar Photometry

|-

|Deidre Hunter

|1986 - Current

|Irregular Galaxies

|-

|Amanda Bosh

|1986 - Current

|Observatory Director, Co-discoverer of Pluto's atmosphere

|-

|Dave Scheicher

|1986 - Current

|Comets

|-

|Will Grundy

|1997 - 2025

|New Horizons Co-Investigator

|-

|Phil Massey

|2000 - Current

|Stellar Astrophysics, Wolf-Rayet Stars

|-

|Lisa Prato

|2005 - 2025

|Young Stellar Objects, Binary Stars

|-

|Stephen Levine

|2010 - Current

|Commisioning and Lead LDT Scientist

|-

|Gerard Van Belle

|2011 - 2025

|High Precision Interferometry, Director of NPOI

|-

|Nick Moskovitz

|2014 - Current

|Near Earth Objects, Meteors

|}

<gallery>

File:Percival Lowell observing Venus from the Lowell Observatory in 1914.jpg|Percival Lowell in the observer's chair of the Clark 24-inch (61 cm) refractor observing Venus

File:Clark Telescope Dome with doors open.jpg|An image of the Clark Dome with its shutter doors opened from US Historic American Buildings Survey in 1994.

File:Alvan Clark Telescope Lowell Observatory.jpg|Historic Clark telescope installed in 1896, used to discover galaxy recession

File:Lowell astrograph.jpg|13-inch (33 cm) astrograph used to discover Pluto prior to restoration

File:Pluto Discovery Astrograph.jpg|13-inch Pluto Astrograph after restoration in 2015

</gallery>

Current research

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 NASA and DLR, the German space agency, and consists of a telescope on board a Boeing 747 SP.

Lowell astronomers, Nick Moskovitz, Brian Skiff, and Tom Polakis also contributed observations in NASA's Double Asteroid Redirection Test (DART) using both the 1.1-meter John Hall Telescope and 4.3-meter Lowell Discovery Telescope. This experiment is the world's first full-scale planetary defense test.

In October 2025, Lowell Observatory announced it would be restructuring its research directives and funding model. Historically, scientists at the observatory were supported with a mix of external grant funding and by Percival Lowell's trust. This model became unfeasable due to a number of factors, including increased operating costs and financial difficulties stemming from construction of the Astronomy Discovery Center. The Observatory has shifted its funding towards more traditional streams, such as grants, endowments, and internally generated revenue. Research at Lowell was trimmed down to exoplanets and planetary defense from near earth objects, led by two Mission Scientists. Current Mission Scientists are Dr. Melodie Kao and Dr. Nick Moskovitz, respectively. Percival Lowell Postdoctoral Fellow are supported through private endowments for four years. Externally funded astronomers and LDT partners may pursue other projects of interest. The number of permanent Mission Scientists is expected to grow and diversify as new funds are secured.

Public programs

In addition to research, Lowell Observatory has a large Public Programs department led by Director Todd Gonzales. Public Programs includes tours of campus, telescope observing, school camps, science talks, museums exhibits, and planetarium documentaries. Guests have access to an array of equipment, historical artifacts, and expertise.

In the 1960s through 1990s, tour guides included Brian Skiff and Robert Burnham Jr., who showed visitors around campus between their regular research duties.

In 1994, the Steele Visitor Center was constructed to accommodate a growing public interest in the observatory. Visitation grew quickly, and new facilities were opened in 2019 with the Giovale Open Deck Observatory and in 2024 with the Astronomy Discovery Center. Public Programs now receives about 150,000 visitors per year.

Around the year 2000, Dr. Amanda Bosh and Dr. Deidre Hunter began the Native American Astronomy Outreach Program (NAAOP). The program pairs scientists with elementary and secondary school teachers from Native American peoples around Northern Arizona to create STEM-centered curriculum. The intent is to encourage student's interest in science careers while supporting Native American educators.

Beginning in 2012, Lowell Observatory began offering camps for children known as Orbits Curiosity Camp. The first camp was established for elementary students. Later on, in 2013, they added an additional camp program for preschool children. The following year they added another program for middle school students. Kids have the opportunity to learn hands-on about science, technology, engineering, and math (STEM) through a variety of activities that include games, experiments, story time, art, music, and more.

In 2015, the historical Clark Telescope was in need of restoration else risk permanent closure. Major donors for the project included the philanthropist Joe Orr and the Toomey Foundation for the Natural Sciences, as well as many individual and group contributions. Funds totalled nearly $300,000. Lowell began a 20-month refurbishment of both the Clark Telescope and the Pluto Discovery Telescope, led by the Director of Technical Services, Ralph Nye. The team worked with the intent of maintaining historical value while ensuring proper function for another century of observing. Some part had to be fabricated, but generally the team was able to clean, repair, and reuse the majority of the originals. Ralph Nye made measurements of the Alvin Clark 24-inch lenses and found they were in nearly the same condition as when ground and polished in 1896, Nye determined they were optically perfect. Restoration was completed in August 2015, the Clark Telescope is now open for public viewing on a regular basis.

In 2016, Kevin Schindler published Lowell Observatory, a 128-page book containing over 200 captions and pictures. Arcadia Publishing's Images of America included it in their series, which increased the enthusiasm of space in the public. The book itself features the popular reputation of Lowell Observatory, encompassing the revolutionary research of scientists and how they contributed to the field of astronomy.

Exhibits

  • The Astronomy Discovery Center: The Astronomy Discovery Center (ADC) is Lowell Observatory's newest facility. It's a 40,000 square foot science center featuring two exhibit galleries, a 180-seat theater with a curved LED screen, roof top stargazing and venue space, a cafe, and giftshop. The ADC was constructed to meet an ever-growing demand for publicly accessible science. Lowell Observatory strives to remain a competitive research facility while expanding its public program operations. This combination of research and outreach make it unique in the world.
  • The Rotunda Museum: Built in 1916, the Rotunda Museum is used by the observatory as a library and collection area for artifacts. It features displays that discuss the Lowell family history and the discoveries made at the observatory. It also houses many different measuring tools including the Blink Comparator used to discover Pluto.
  • Putnam Collection Center: The Putnam Collection Center is open to the public once per day during a guided tour of the facility. The Center highlights the Observatories history and features artifacts from Lowell's past, including the spectrograph used by VM Slipher. Guests may view 'Big Red' here, which was Percival Lowell's 1911 Stevens-Duryea motorized vehicle. Inside is a classroom space with displays on light pollutions and the Messier Objects. It's here that the Astrophotography classes and Telescopes 101 classes take place.

Permanently mounted telescopes at the GODO

  • 5.5-inch TEC apochromatic refractor
  • 8-inch Moonraker 'Victorian' achromatic refractor
  • 32-inch Starstructure reflector
  • 14-inch Celestron EdgeHD SCT
  • 14-inch PlaneWave astrograph
  • 17-inch PlaneWave astrograph

Other GODO telescopes

  • 100 mm Lunt Hα solar telescope
  • 8-inch Orion reflector
  • Two 12-inch Teeter reflectors
  • 16-inch Teeter reflector
  • 16-inch Meade SCT

The Dyer Telescope

Housed in its own aluminum dome, this 24-inch (61 cm) PlaneWave CDK catadioptric reflector is used for nightly private observing events. An educator guides guests through views of galaxies, clusters, planets, and nebulae over the course of an hour and fifteen minutes. The dome was once called the McAllister Dome, housing a 16-inch Boller and Chivens cassegrain telescope from 1963. The McAllister telescope was used for public viewings beginning in 1999 before falling into disrepair. Funds for a new telescope were given in honor of Brian Dyer. In the future the Dyer will be equiped with scientific instrumentation.

Other

alt=The 20-inch Apollo Telescope|thumb|The Apollo 20-inch (50 cm) refractor used by Lowell Observatory and ACIC for the Lunar Mapping project.

thumb|A detailed view of the Clark Telescope's control mechanisms.

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 Clark Refracting Telescope, which is now used for public education, with 150,000+ annual visitors. The telescope, built in 1896 for $20,000, was assembled in Boston by Alvan Clark & Sons and then shipped by train to Flagstaff. The Apollo Telescope, a 51 cm (20-inch) refractor, used for the Lunar Mapping project is on Mars Hill but has been decommissioned. Also on display is the Pluto Discovery Telescope, used by Clyde Tombaugh in 1930 to discover the dwarf planet Pluto.

In 2014, the Putnam Center was opened. This observatory included many rooms with tools that were useful to observers including a library for research, a room for processing photographic glass plates, multiple antique instruments used by previous astronomers, and many artifacts. The observatory does contain areas that are closed to the public view, although there are multiple places that tourists are welcome to visit.

  • Large recessional velocities of galaxies by Vesto Melvin Slipher between 1912 and 1914 (that led ultimately to the realization our universe is expanding)
  • Co-discovery of the rings of Uranus in 1977
  • The periodic variation in the activity of Comet Halley during the 1985/1986 apparition
  • The three largest known stars
  • The atmosphere of Pluto
  • Accurate orbits for two of Pluto's moons: Nix and Hydra
  • Oxygen on Jupiter's satellite Ganymede
  • Carbon dioxide ice on three Uranian satellites
  • The first Trojan of Neptune
  • Evidence that the atmosphere of HD 209458 b contains water vapor

See also

  • List of astronomical observatories
  • List of largest optical telescopes in the continental United States

References

;Footnotes

; Sources

  • Strauss, David (2001), Percival Lowell: The Culture and Science of a Boston Brahmin, Cambridge: Harvard University Press, ,
  • Hoyt, William Graves (1996), Lowell and Mars, Tucson: University of Arizona Press, ,
  • Putnam, William Lowell (1994), The Explorers of Mars Hill: A Centennial History of Lowell Observatory, 1894–1994, New Hampshire: Phoenix Publishing, ,
  • Lowell Observatory
  • Lowell Observatory Camps for Kids
  • Lowell Discovery Telescope
  • Flagstaff Clear Sky Clock Forecasts of observing conditions covering Lowell Observatory.
  • National Historic Landmarks Program: Lowell Observatory
  • Wonderdome Mobile Planetarium Blog

;Historic American Buildings Survey (photographic survey)