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The Rotunda Museum

Housing some of the most precious artifacts of Lowell Observatory’s history, the Rotunda Museum was completed in 1916 and served as the institution’s library until the mid-1970s.

The Rotunda features several important displays concerning:

  • The discovery of Pluto in 1930 by Clyde Tombaugh.
  • V.M. Slipher’s discovery of large recessional velocities of galaxies starting in 1912 (that led ultimately to the realization our universe is expanding).
  • Lowell Observatory’s role in mapping the moon for the Apollo Program. Maps were created on campus, and many noted astronauts visited Lowell during a training session in 1963.
  • Percival Lowell’s research of Mars – including notes, drawings, and globes – and the influence his work continues to have, both on scientific research and popular culture.
  • The Lowell family and its rich history.

The Rotunda is also home to various measuring and calculating devices including a Thacher’s Calculating Instrument, a huge slide rule (the precursor to calculators) with a folded scale 60 feet in length.

Lastly, suspended from the ceiling of the dome is the Saturn Lamp, a stained-glass marvel constructed in 1918 by the Los Angeles Light Company.

The Putnam Collection Center

While the library and collections areas are closed to the public, the building lobby contains displays that guests may visit. This area is open to the public from 1 – 2 p.m. daily. They highlight the Observatory’s history and feature selected items from the collections, including:

  • Percival Lowell’s first telescope, which his mother gave him when he turned 15 years old.
  • The spectrograph that V.M. Slipher used to capture the first evidence of the expanding nature of the universe.
  • Percival Lowell’s hand-drawn Mars globes showing details including the supposed canals.
  • Instruments built by Lowell scientists and used for measuring the physical characteristics of celestial bodies.
  • Classic scientific books dating back decades to centuries.
  • Digital Archives can be found at the Arizona Memory Project
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