As a research scientist at the Planetary Science Institute, Kat Volk finds the study of exoplanets as fascinating today as when she was in high school and first became interested in planets that lie beyond our own solar system.
When she was in school, pulsar planets had been discovered, but exoplanet research was just heating up. Today, there are more than 5,000 known exoplanets, and researchers in the field are constantly uncovering something new.
These new findings can help educators illustrate to students how knowledge itself can evolve — and that science is not carved in stone.
“A long time ago our solar system was the only planetary system we had to look at,” Volk said. “We know a lot about the solar system, but it still doesn’t answer questions of how typical our solar system is, how did we end up with a nice habitable planet, a nice breathable atmosphere, and how did we get here?”
Most students understand what a planet is, maybe having crafted model solar systems at some point. Exoplanets, however, are those that exist outside our solar system. They’re not as visible as Mars or Saturn from Earth, but can be discovered by what they leave behind when they pass, or transit, in front of their sun — a dip in light.
Elisabeth Adams, senior scientist at the Planetary Science Institute, acknowledges it would be easier for younger students to engage with exoplanets if they had more “kid-friendly names.” Exoplanets are typically named with codes that start with the telescope used to find it, then by their star, and then with letters in order of the exoplanet’s discovery, such as exoplanet HD 189733 b.
One way to get students, especially younger ones, to think about exoplanets is to start with dwarf planets in our own solar system that have more approachable names, Adams said. For example, she recently talked with kindergartners about Ceres, located in the asteroid belt between Mars and Jupiter, and Sedna, located in the Oort Cloud, three times further from the sun than Pluto. From there, educators can begin to talk about planets further away, even with names that look like code.
“But apart from the name issue, once kids have an understanding of what the solar system is like, it's pretty easy to find interesting exoplanets to compare and contrast with,” Adams said. “Planets that orbit two stars. Planets that are so close to their star that their atmospheres are being stripped away. Planets that float free in space."
What exoplanets teach us about Earth
Exoplanets, and even our own planet, are constantly in a state of flux. "By looking at thousands of exoplanets in different situations, we can understand and learn more about the evolution of an atmosphere and the impact it has on that planet's environment,” said Hannah Wakeford, a senior lecturer in astrophysics at the University of Bristol in the United Kingdom.
These studies can help scientists — and students — gain insight on whether there is life on other planets and identify other worlds that could be habitable and potentially the different kinds of environments where life could exist, said Peter Buhler, a research scientist with the Planetary Science Institute. That information could also help those studying climate changes on Earth.
“By studying exoplanets that have undergone significant environmental changes, such as those that have lost their atmospheres or experienced extreme climate shifts, scientists can gain insights into the environmental challenges facing our own planet and develop new approaches for addressing them,” Buhler said.
To engage older students in grasping what's currently known about exoplanets and solar systems, he suggests teachers use online visualizations of exoplanets and their suns, found through Kepler since 2011, that are hosted on NASA’s website. Buhler said that for middle and high school students, this can help to illustrate “the diversity of exoplanetary systems.”
With younger students, he suggested educators consider using two videos. One is “Powers of Ten,” which increases tenfold magnification every 10 seconds going from 100 million light years into space, down to the proton of a carbon atom in less than 10 minutes. The second, HTwins.net, allows students to zoom in and out from the observable universe down to Planck length — the smallest size in the universe — related to quantum mechanics.
Science is always changing
The study of exoplanets can help educators explain how the long-held theory of our solar system’s formation has started to change. Volk said scientists had believed rocky planets like Earth and Mars formed close to the sun because the rock and metal at their cores would have been able to remain solid at higher temperatures. And planets like Jupiter and Saturn that are further away from the sun, where it is cooler, were formed of ice and gases.
“But now we’re finding planets with gas, like Jupiter, right next to a sun,” said Volk. “We don’t entirely understand how that works for formation, but we see them.”
To Volk, studying exoplanets is a good mirror for the world of science — and a way for classes to understand there are always more questions to ask and new observations to make. She noted that with every discovery — especially around exoplanet research — scientists have to rethink their theories, and readjust what they know. That is a good lesson for students to learn, too, she said.
“I always love to emphasize to students that it’s okay when our ideas come up wrong,” Volk said. “It’s about testing. It’s exciting when we’re wrong. If we do everything right, we would be out of jobs, and there would be no more questions.”