The world is a book, and those who do not travel read only one page.
Saint Augustine
Lowell Observatory
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Lowell Observatory Rotunda Library
At the end of the Pluto tour we spent some time watching a movie in the 3-D digital theatre where we learned more about the 100 years of celestial research on Mars Hill then joined another group for the Mars tour. This tour included a visit to the historic Rotunda Library where we saw some of the original astronomical research tools.

Displays include the Millionaire, one of the earliest motorized calculating machines, used at the Lowell Observatory from about 1914 to the early 1930s. Percival Lowell’s assistants, known as ‘computers’ at the time, devoted seven years to making mathematical calculations to test different astronomical projections that led to the discovery of Pluto. Work done on that early machine could be completed today in a matter of hours by today’s computers using high-speed microprocessors.
Millionaire motorized calculating machine

A display cabinet in the Rotunda Library shows several historic instruments used in early astronomical research. On one of the shelves is a 1920s Clock Drive used to regulate the motion of a telescope as it tracks the stars and planets during the course of the night.
On another shelf is Thacher’s Calculating Instrument, a slide rule commonly used many years ago to make rapid mathematical calculations. Much larger than the typical ten inch scale slide rule, the Thacher slide rule unfolds to a mighty sixty feet in length thus significantly increasing the accuracy needed for astronomical data analysis.

Also among the displayed antique items was a Radiometer. When light from a star or small area of a planet was focused on the sensor of the Radiometer, astronomers could use the generated minute electric current to estimate the radiation and temperature of the far away objects. Along
Lowell Observatory Clark Domewith these and numerous other items used in the Observatory’s pioneering research, the Rotunda Library contains volumes of priceless books on astronomical theories and research.

The Mars tour also stops at the Clark Dome just up the hill from the Rotunda Library. Inside the Dome is the 24-inch refracting Alvan Clark Telescope, purchased for 24 thousand dollars in 1909 but would cost more than 70 billion dollars today. To track celestial targets, the massive 11-ton telescope projects through an opening in the dome’s rAlvan Clark Telescopeoof and can be rotated into position with the assistance of automobile tires. Sitting on an elevated platform is the chair used by Percival Lowell during his many hours of watching the heavenly bodies.

At one time the Clark Dome also provided ideal climatic shelter for thermometers, hygrometers (to monitor humidity) and other weather station instrumentation used to understand and predict weather patterns necessary in planning successful observations. That instrumentation was removed in the latter part of the 20th century and replaced with a modern weather station located on top of the Clark Dome. Nearby on a shady hillside facing Mount San Francisco is the mausoleum containing the remains of Percival Lowell who died on November 12, 1916.
 mausoleum containing the remains of Percival Lowell
Everything that we heard and saw during the tours and the movie set the stage for observing the night sky as we’d never seen it before.

The red landscape lighting along the center’s pathways focuses downward and visitors were asked not to use flash photography to ensure that our pupils were fully open when it was our turn at the telescope. With t
he assistance of our guide, each of us climbed the short step ladder and peered expectantly through the telescope’s eyepiece. There was a long line so each of us had less than a minute to view the craters on the edge of the nearly full moon; craters created eons ago by the impact of asteroids. Awesome, cool, wow and other superlatives were expressed by young and older alike. When everyone had seen the moon up close, the guide located Saturn, focused the telescope then invited each of us to climb the ladder again to view the rings around Saturn. It was fantastic, much better than any picture I’d ever seen.

Each year more than 80,000 visitors find their way up Mars Hill to the Lowell Observatory. I’m sure that, like me, most of them leave with a profound respect for the work led by Percival Lowell and his staff of astronomers to document the wonders of outer space.

The Observatory is funded with donations from private sources. It was designated a Registered National Historic Landmark by the US Department of Interior National Park Service in 1966. Admission fees are $8 for adults, $7 for seniors, AAA members and college students; $4 children (ages 5 – 17). If you come during the daytime, simply show your receipt for reentry for the evening program.

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Scenic Rim Tour

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