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Using the language of human development to describe how galaxies come into being, we say they are born, mature, change and age.

But the scale of galactic development is mind-blowing. Galaxies both new and mature exist millions, even billions of light years away, and take millions of years to grow and evolve. And of course, galaxies undergo vast physical and chemical transformations along the way. Given that, how do we know what we know about the birth and growth of galaxies?

Michael Maseda

That’s where Michael Maseda comes in. UW’s newest assistant professor of astronomy specializes in charting the formation and development of galaxies outside our own Milky Way. Using powerful telescopes and spectroscopy, a means of identifying and measuring the gasses in a galaxy through charting the wavelength of the light waves they emit, Maseda studies images of hundreds of galaxies, trying to answer some of the thorniest questions about how they began.

“I think, philosophically, astronomy is a very interesting field because it's a physical science, but it's also actually a lot like a social science,” says Maseda, who joined the Department of Astronomy earlier this year. “If I’m watching a galaxy, nothing is going to change in my lifetime. So I do a sort of population study. I take observations of galaxies and try to see how they grow.”

For the past several decades, those observations have largely come from images of galaxies generated by NASA’s Hubble Space Telescope. Given the vast numbers of galaxies in the universe—remember, we’re talking millions—the Hubble zooms in on a small area of the sky over a period of several days, using it as a stand-in for the universe at large. The image, which contains 10,000 galaxies, is known as the Hubble Ultra Deep Field.

On December 24th, NASA will launch the James Webb Space Telescope, the long-awaited successor to the Hubble Telescope (here's a link to watch the scheduled 6 a.m. launch). The new telescope features a larger mirror and more sophisticated instrumentation than the Hubble had, allowing researchers to capture even more detailed images that could help define even more distant galaxies.

Thanks to Maseda’s association with the European Space Agency, the intergovernmental organization where he spent the last six years as part of a team of scientists that planned and coordinated the Webb Space Telescope’s science program, Maseda earned the opportunity to use it for two projects. One will use the telescope’s powerful spectrograph to collect more information about galaxies that are just beginning to form stars. Maseda is particularly interested in the stars’ chemical composition.

“After the Big Bang, the universe was mostly hydrogen and helium gas,” Maseda explains. “So any element that's not hydrogen or helium has been produced inside stars. We don’t understand young stars in the early universe very well from a physical perspective. These observations will be helpful in characterizing the stars themselves, and once we understand the stars we can start to understand this nascent population of galaxies a bit more.”

Before coming to UW-Madison, Maseda worked as a scientific researcher at the Leiden Observatory in the Netherlands, using the advanced suite of space telescopes controlled by the European Southern Observatory to explore younger galaxies.

“What we typically ended up seeing is that these teenaged galaxies had these growth spurts, so they would be growing really quickly for short periods of time. That’s not how a galaxy like our Milky Way grows today,” he says. “They grow very quickly for a very short period, and then they stop. And that was new. We didn't necessarily know that.”

Maseda was lured to Wisconsin by UW-Madison’s long tradition of space-based astronomy—the use of telescopes launched into space to study the universe. He was also drawn to the department’s spirit of collaboration, as well as the fact that it’s currently in growth mode, participating in an ongoing, multi-departmental hiring process focused on attracting experts who explore the origins of life. The Webb telescope, and Maseda’s expertise with that and many other areas, will play a key role.

“The hope is that we can significantly shape the scientific output from the Webb,” says Maseda.