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.