A New Astronomy Programs Helps Young Minds Tackle Big Questions

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• Michelle Franklin- m1franklin@ucsd.edu

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How does a child who looks up in amazement at the stars in the night sky grow up to become an astronomer trying to uncover the nature of dark matter? What kinds of support and inspiration do they need along the way? It's a question one University of California San Diego astronomy professor is trying to answer with a new program that shows high school students how to combine the power of data science with the wonders of the universe.

Ethan Nadler, an assistant professor in the Department of Astronomy and Astrophysics, remembers from his own education that he wasn't exposed to astronomy as science until he was in community college. Now a computational astrophysicist who specializes in galaxy formation and dark matter, he knows that engaging students earlier increases the likelihood they will pursue a career in the field. With this in mind, he launched an eight-week course, called "AstroReach SD: Dark Matter & Python," for students at The Preuss School UC San Diego.

The Preuss School is a charter middle and high school on the campus of UC San Diego. It enrolls low-income students from San Diego County who aim to become first-generation college graduates. The school does not currently have a class solely focused on astronomy, so Nadler proposed his course to science teacher Johnathan Chittuluru, who teaches AP Computer Science Principles to juniors and seniors.

Nadler wanted the students participating in his course to indulge their intellectual curiosity about the universe - what it's composed of and how dark matter fits into that picture - while also learning scientific computer programming skills - useful whether or not they pursue astronomy as a career.

"I wanted to present astronomy in a way that's accessible - to show them that it's not just complicated math, and that we can all build an understanding of the universe together," stated Nadler. "And practically speaking, developing Python skills early on is really useful no matter what they do in the future."

Everything goes through code

Astronomical data is digital. Today, satellites and telescopes record massive amounts of data, which can't be sorted manually. In order to extract the information from the datasets that computational astrophysicists use in their predictions, they build code to run the algorithms necessary to parse the data.

Even though the Preuss students learned Python in their computer science class, using it to read files or design webpages, it requires something different for research. Nadler showed students how to tailor Python for scientific functions, such as calculating a standard deviation or plotting variables against each other.

"As a computer-science educator, it's gratifying to see that a phenomenon as complex as galaxy formation could be understood at a high level through the application of straightforward Python computation and probed at fine detail through advanced computational simulation," stated Chittuluru.

As part of their coursework, students ran simulations on a longstanding physics challenge called "the three-body problem." In it, students tried to predict the motion of three celestial bodies under the influence of their own gravity. As students changed the masses, speed and positions of the bodies they realized something physicists have known for hundreds of years: the problem is not generally solvable and the systems they created quickly became chaotic.

"The reason they learn about the three-body problem is because, at a basic level, this is how we run dark matter simulations," said Nadler. "It's just that instead of using three particles, we use three billion."

Visualizing the invisible

Dark matter makes up a significant portion of the universe. Although it has not been directly observed, there is evidence it exists. When scientists observe galaxies, they notice some rotate faster than expected, so they infer that there is an unseen mass affecting its rotation. The unseen mass is dark matter.

"No one knows what dark matter is, but that's why I'm so interested in it. I like to convey the sense of wonder - we don't know what most of the universe is made of!" Assistant Professor of Astronomy and Astrophysics Ethan Nadler

Nadler points out that dark matter isn't a placeholder for the "real" answer yet to come: "We have vast datasets of how galaxies are distributed throughout the universe, how they rotate, pictures of the early universe - it overwhelmingly points to the same dark matter model."

For their final project, Nadler wanted students to combine the course objectives: gaining a basic understanding of the universe and how astronomical research is conducted and developing hands-on Python skills to analyze datasets. To do this, students created visualizations of dark matter simulations, which were printed and handed out during the final session.

Students were able to choose from a variety of simulations taken from various regions of the universe and then generated the code to customize the visualizations how they wanted. They were able to input data, plot the dark matter density and then adjust the color and contrast to suit their own aesthetics.

Everyone received prints of their visualizations on the last day of class, which took place at UC San Diego's Science and Engineering Research Facility. Students toured two astronomy and astrophysics professors' labs - Steve Boggs's High Energy Astrophysics lab and Shelley Wright's Optical and Infrared lab - before lunch and an afternoon of lectures, given by the department's postdoctoral scholars, and graduate and undergraduate students. Some undergraduates have even been paired with Preuss students to provide mentoring and advice on applying to college.

Students came away from the course inspired. Junior Dominic Au said, "AstroReach not only allowed me to see what coding looks like when applied to astrophysics, but also provided insight on what college lectures and pacing feel like in astronomy."

The program was funded by the School of Physical Sciences and Nadler hopes to expand in the coming years to include other areas of space science. He also wants to give postdocs the opportunity to teach some of the classes - something he found rewarding when he was a postdoc at Carnegie Observatories and the University of Southern California.

Chittuluru thinks this was a unique opportunity for his students, saying, "During this course, they were introduced to scientific presentations and laboratory research. Few high-school students, especially from the demographic Preuss serves, are afforded such transformative experiences."