The City of Frankfort installed a marker commemorating the accomplishment of two world-famous astronomers from Clinton County. The marker was erected in cooperation with Lowell Observatory in Arizona, Camp Cullom’s Prairie Grass Observatory, Frankfort Mayor Judy Sheets, Frankfort City Council, Clinton County Historical Society/Nancy Hart, Historian from the Goethe Link Observatory and Indiana Astronomical Society Tom Borlik, Wabash Valley Astronomical Society and others.
A pair of Clinton County farm boys who helped change humanity’s understanding of the universe now have a rare Indiana State Historical Marker erected in their hometown.
A new Indiana State Historical Marker honoring astronomers Vesto and Earl Slipher was erected in front of Old Stoney today, where the nationally famous brothers went to High School years ago.
The markers were dedicated this summer during the Indiana Family Star Party on August 8th at Camp Cullom’s Prairie Grass Observatory. The dedication program was led by Kevin Schindler, historian and public information officer for Lowell Observatory in Flagstaff, Arizona, where the Slipher brothers spent their celebrated careers. Dr. Catherine (Caty) Pilachowski, Distinguished Professor of Astronomy from Indiana University participated in the dedication and will also spoke at the Astronomy gathering at Camp Cullom earlier this year.
The New Marker is one of only two Historical Markers in Clinton County. The other Indiana Historical Marker stands in front of Case Arena, in honor of Evert Case, nationally famous basketball coach who brought four state basketball titles to the City of Frankfort.
Vesto (1875–1969) and Earl (1883–1964) Slipher grew up in Clinton County and graduated from Frankfort High School before continuing their studies at Indiana University, then heading west to join Lowell Observatory near Flagstaff, Arizona. From those small-town beginnings, their work would reshape modern astronomy.
At Lowell, Vesto Slipher was among the first astronomers to systematically measure the spectra of spiral nebulae—what we now know are distant galaxies. His careful measurements of galactic redshifts in the 1910s and 1920s provided the first strong observational evidence that most galaxies are racing away from us, laying the groundwork for the modern theory of an expanding universe later associated with Edwin Hubble. Vesto also confirmed the existence of interstellar gas and dust and discovered reflection nebulae, proving that space between stars is far from empty.
Earl Slipher became one of the world’s leading experts on the planet Mars. Over more than five decades, he led major observing campaigns and photographic expeditions, including trips to observatories in South Africa to capture high-quality images of Mars at opposition. Earl’s pioneering planetary photography produced some of the earliest and best color images of Mars, helped document seasonal changes such as polar caps, clouds, and dust storms, and culminated in an influential volume often cited by later planetary scientists.
CLICK HERE for information about Crater on Mars Named after Sliphers.
CLICK HERE for information about Lunar Crater Named after Sliphers.
Together, the Slipher brothers’ work provided crucial evidence that the universe is expanding, revealed the nature of the material that fills interstellar space, and advanced our understanding of the planet that would become a prime target for space exploration. For astronomers around the world, their names are woven into the story of modern cosmology and planetary science.
The new two-sided historical marker, now erected in Frankfort, summarizes that story and ties it back to the community where it began. One side highlights the brothers’ Clinton County upbringing, their Frankfort High School and Indiana University educations, and their long careers at Lowell Observatory. The reverse side explains Vesto’s spectroscopic work that provided observational evidence for an expanding universe and the existence of interstellar gas and dust, as well as Earl’s groundbreaking Mars photography and international observing expeditions that produced some of the earliest color images of the Red Planet.
A site near the Frankfort City Building “Old Stoney” was selected so residents and visitors can easily see the marker and learn how a story that stretches from Indiana cornfields to Arizona mountaintops and South African observatories began in Frankfort and Clinton County. The Slipher Brothers attended High School at Old Stoney before it became home for the City of Frankfort administration. The marker now stands as a daily reminder that world‑class science can grow from small Midwestern communities.
When you hear the term “expanding universe” and “red shift” , know Vesto Slipher not only had a front row seat to this research, but actually laid the foundation for important work in astronomy that stands today, while Earl’s research contributed to our early observational knowledge of Mars.