History in My Hands

The featured program at last night's monthly meeting of the Coconino
Astronomical Society was a behind the scenes tour of Lowell Observatory led by
Kevin Schindler. Schindler is the educational program supervisor at Lowell. In
addition to developing programs for school groups, Kevin has an intimate
knowledge of the observatory's history. He performs as Percival Lowell in a
one-man show about the observatory's founder and has written a history of the
24-inch Clark refractor. Kevin's tour took us to facilities not included in the
program for the general public and concluded with a visit to the archival vault
in the basement of the Slipher building.

It is in the Slipher building vault where the photographic plates made with the
13-inch Lawrence Lowell astrograph are stored. These include the original
discovery plates for Pluto. As a former member of the public program staff at
Lowell, I'd given and heard this portion of Kevin's presentation several times.
So, while the others in our group were focused on Schindler's re-telling of the
events that took place around Tombaugh's discovery of our Solar System's most
distant planet, my focus wandered to a shelf of notebooks near where I was
standing.

The notebooks were labelled "Spectrograph Logs." The fist notebook had a white
paper tab sticking out from a page near the back. I carefully pulled the small
hardbound booklet from the shelf and read the tab, "And. Neb." Immediately, I
sensed that this might be a record of the one of the most significant
scientific discoveries of the 20th century. Flipping to the tabbed page
confirmed that suspicion.

Vesto M. Slipher, the namesake of the building in which we were standing, was
the first person to make spectrographic observations of galaxies beyond the
Milky Way. He did his work with a Brashear spectrograph attached to the back
end of the 24-inch Clark refractor. Arguably, the most significant observation
he made in this field was that of December 30, 1912 to January 1, 1913.

Over the course of two nights, Slipher made an exposure recording the spectrum
of M31, better known as the Andromeda Nebula in those days. Analysis of this
spectrum revealed that M31 was moving through space at a rate surpassing that
of any other known object. Throughout the remainder of the second decade of the
20th century, Slipher made spectral observations showing that all the spiral
nebulae had motions as fast or faster than the Andromeda Nebula. This turned
out to be the first solid evidence that these objects resided far beyond the
Milky Way. And more than a decade later, Edwin Hubble would cite Slipher's work
as being crucial in his development of the theory of an expanding universe.

Reading the handwritten notes in that booklet, I could see that Slipher had
exposed a chemically treated glass slide for a little longer than 4 hours the
first night, and had continued the exposure for nearly 7 hours the following
night. In total, he had manually guided the 24-inch Clark through an 11-hour
exposure to record this galaxy's spectral bar code. I wondered if he had
entered these notes at the end of two very long and tiring nights' work; if he
had felt a sense of discovery when first seeing the spectrum; and how long it
had taken before he came to the conclusion that such incredible rates of motion
could only be explained if the objects were far beyond our home galaxy?

What a remarkable experience that was for me, to finish a very special tour of
Lowell Observatory with a real piece of history in my hands.

Regards,
Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
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