Kevin Schindler Unveils Secrets Behind Pluto’s Discovery

During a recent presentation at the Sedona Heritage Museum titled “Tiny Pluto Has a Big Heart,” Lowell Observatory Historian Kevin Schindler engaged audiences with a deep dive into Clyde Tombaugh’s discovery of Pluto and its significance in both scientific research and pop culture.

Schindler traced the history of Pluto’s observation, beginning with its 1930 discovery from Flagstaff, and highlighted the groundbreaking 2015 New Horizons mission that imaged the dwarf planet. Of special note, he mentioned Pluto’s designation as Arizona’s state planet, set for March 2024.

“In 1781, William Herschel discovered Uranus, the first planet identified through a telescope,” Schindler stated. “Its observed wobble led astronomers to suspect another planet’s gravitational influence. This speculation culminated in Neptune’s 1846 discovery, but questions remained, prompting the search for a ninth planet.”

He emphasized Tombaugh’s role in Pluto’s discovery, suggesting it might have been delayed until the 1980s had it not been for Tombaugh’s meticulous approach using time-lapse photography. “Other scientists didn’t have the patience,” Schindler explained, reflecting on Tombaugh’s use of a blink comparator to detect subtle changes among 300,000 stars.

Significantly, Schindler noted that Pluto’s understanding expanded dramatically on June 1978 with the discovery of Charon, its largest moon, by James Christy and Robert Harrington at the U.S. Naval Observatory. Christy noticed an unusual blob in images of Pluto, which led to the eventual confirmation of Charon. Its name pays homage to Christy’s wife as well as the mythological ferryman.

“When a moon orbits a planet, it provides critical data for understanding the planet’s mass,” Schindler remarked. The discovery of Charon allowed astronomers to refine their estimates on Pluto’s size, dismissing earlier comparisons to Jupiter.

The landscape shifted further in 2006 when the New Horizons mission launched on January 19, coinciding with the International Astronomical Union’s redefinition of what constitutes a planet. Schindler expressed his views on this reclassification: “Some argued that calling Pluto a planet was absurd, especially with the discovery of other similar-sized bodies.”

Per the IAU, Pluto was reclassified as a dwarf planet because it fails to meet one key criterion: it has not cleared its neighborhood of other objects. “Pluto has a moon, an atmosphere, and certainly seems planet-like,” Schindler said, advocating for a more inclusive definition based on how celestial bodies appear to us.

In discussing the significance of the New Horizons mission, Schindler shared the challenges faced during its development. “This was the fastest-moving spacecraft on record, traveling at 36,000 miles per hour,” he explained, drawing parallels to the influence of the Voyager missions of the 1970s on young explorers. He mentioned Tombaugh’s ashes being carried on the spacecraft, connecting personal passion for space exploration back to Tombaugh’s childhood curiosity.