The sky’s the limit

URI teaching professor of astrophysics Doug Gobeille
In Doug Gobeille’s courses, students are encouraged to breach the limits of the imagination. Photo by Nora Lewis.

“Heads up, UNC Chapel Hill: URI is coming for your Guinness world record for highest Galilean cannon launch.”

Professor of astrophysics Doug Gobeille proclaims this with the spiritedness of a 10-year-old boy thirsty for a schoolyard dustup.

The Galilean cannon is a simple demonstration of the principle of conservation of linear energy in which three balls of different weights are stacked (heaviest on the bottom to the lightest on top) and dropped, transferring energy to, and launching the topmost ball.

But Gobeille’s enthusiasm for this project isn’t just about Galilean cannon record-breaking; it characterizes his approach to instruction in all his courses, from introductory to upper level. Essentially, Gobeille wants students to feel the same excitement he does for everything from supermassive black holes (his area of expertise) to the tiniest asteroids.

Gobeille, who grew up watching Carl Sagan’s Cosmos on PBS, seeks to inspire the same sense of wonder in his students that Sagan inspired in him. Students in the introductory course, Astronomy 108: Stars and Galaxies, for instance, received extra credit on an exam for attending a lunar lab one night this past spring. They gathered around a telescope on the Quad to look at Jupiter and the moon. Murmurs of “Cool” and “Wow” could be heard as students fell back in line for a second and third look—no small thing when the temperature was below freezing and the line nearly 50 students deep.

They even stayed in the cold a little longer to chat with Gobeille about how to tell satellites from airplanes in the night sky (hint: satellite lights don’t blink).

To Mars and back

In upper-level courses such as Physics 491: Astrodynamics, students are using software to simulate the building, testing, and launching of rockets that would land astronauts safely on Mars and return them home. For this assignment, students “just” have to launch their rockets and get their missions to Mars and back; they don’t have to worry about some of the important details—like safety and food. 

And if you think planning a there-and-back mission to Mars or breaking a world record seems wildly out of the scope of what students could possibly achieve during a single semester, you’re right. Gobeille grins at the suggestion that these are challenges designed to keep students coming back for more.

“For now, we’re worrying about the rockets,” Gobeille says. “But students can come back, take another course, and I’ll throw much harder problems at them.”
What kinds of problems? “Things breaking, for example,” he says, and laughs. “That’d be so fun.”

As for that world record for highest launch of a Galilean cannon?

The physics and engineering students in Gobeille’s Physics 492: Practical Classical Dynamics will be refining and testing Galilean cannon prototypes this summer.

“The objective is height. I really want a high enough launch that we’d need Federal Aviation Administration clearance, which means over 1,000 feet,” Gobeille says.

But the record to beat is just 13 meters, or 42.6 feet. Surely, talking about FAA clearance is overkill?

“I don’t think so,” Gobeille grins again. “Launching over 1,000 feet wouldn’t be that hard.”

Marybeth Reilly-McGreen

The Wonders of Space: A Self-Study Guide


Rocket (or Galilean cannon) building, star gazing, the existence of extraterrestrials (pretty unlikely, Gobeille says), even the topic of death by exposure to outer space (it’d be unpleasant, according to Gobeille)—these topics and more are fair game in Gobeille’s classes, including a science fiction course he co-teaches with film/media professor Rebecca Romanow. He suggests the following books, films, and series for anyone interested in expanding their horizons.


Childhood’s End by Arthur C. Clarke. Aliens colonize the planet and end poverty, hunger, and disease. Then the trouble begins.
Contact by Carl Sagan. Scientists set out to find the source of a signal from outer space.
Do Androids Dream of Electric Sheep? by Philip K. Dick. A bounty hunter fights androids disguised as humans.

The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan. A case for scientific thinking as a means to preserve our democratic institutions.

Stream and Watch

Film and TV
Altered Carbon. A series based on the book by Richard Morgan. A prisoner is given a new body and asked to solve a murder in return for his freedom.
Black Mirror. A sci-fi series exploring the drama and, occasionally, horror stemming from human interaction with technology.
The Twilight Zone. The original 36-episode sci-fi series (1959–1960).
Rick and Morty. An Emmy-winning animated series about the intergalactic adventures of a sociopathic, time-traveling scientist and his hapless grandson.
Cosmos. Astrophysicist Neil deGrasse Tyson discusses the wonders of the universe.

Kurzgesagt—In a Nutshell. Visit the Kurzgesagt channel on YouTube for short, fun videos about things like war in space, solar storms, black holes, and gamma ray bursts. Gobeille’s watch list: “Grabby Aliens,” “Grabby Aliens—Predictions,” and “How to Take Over the Universe (Eternity in 6 Hours).”