View From Mars Hill: Progress in Understanding the Pluto System
As published in the Arizona Daily Sun on 8/14/2025
Boy, how the world has changed over the past 10 years — but perhaps not as profoundly as our understanding of another, more distant world that holds a special place in the hearts of northern Arizonans: Pluto. Last month marked the 10th anniversary of NASA’s New Horizons mission, which revolutionized our scientific understanding of Pluto and its family of moons while captivating the global imagination with stunning imagery.
To commemorate this landmark event, some 100 scientists gathered at the Applied Physics Laboratory (APL) in Laurel, Maryland — with many more joining remotely — for a conference titled Progress in Understanding the Pluto System: 10 Years After Flyby. Held from July 14–18, the conference featured more than 80 science presentations and posters exploring Pluto and its five moons, along with a public evening program hosted by members of the New Horizons team and student-led sessions.
A highlight of the conference took place on the evening of July 14. It was on this date in 2015 that the New Horizons spacecraft flew by Pluto and captured its iconic images that mesmerized people around our own globe. At that moment, Pluto was no longer a dot against the backdrop of thousands of other dots, but a vibrant world with icy mountains, a complex atmosphere, and a smooth, heart-shaped feature soon to be named Tombaugh Regio after the Flagstaff scientist who discovered Pluto in 1930.
A legendary, later-generation Flagstaff scientist joined the July 14 festivities and drew the attention of modern-day students and astronomers alike. His name is Jim Christy, and in 1978 he discovered Pluto’s largest moon, Charon, off photographic plates captured at the Naval Observatory Flagstaff Station. Jim was joined at the event by his wife Charlene and son Randy, and spent much of the evening surrounded by scientists of all ages anxious to speak with him about his great discovery and take a selfie with him.
Flagstaff was well represented in Laurel. Planetary scientist Will Grundy and historian Kevin Schindler of Lowell Observatory presented programs, as did Northern Arizona University’s Professor Josh Emery, graduate student Lucas McClure, and undergraduate student J.J. Melendy. Graduate student Ana Morgan also presented remotely.
The New Horizons mission yielded a treasure trove of insights, including: Tombaugh Regio — a nitrogen-rich, heart-shaped region; active geology with icy mountains, glaciers, and evidence of internal activity; atmospheric hazes with layers of misty haze in Pluto’s thin atmosphere; wind-sculpted dunes formed from icy particles; a possible subsurface ocean beneath Pluto’s crust; Charon’s features, including deep chasms and a red-colored polar cap; and Arrokoth’s shape, a two-lobed Kuiper Belt object that New Horizons flew by on its extended mission in 2019.
Beyond its scientific achievements, New Horizons rekindled public fascination with space exploration. For the first time since the Voyager missions to Jupiter, Saturn, Uranus, and Neptune, humanity witnessed a world up close for the first time.
Participants in the conference do the “Pluto Salute.”