Dr. Charles Liu, an astrophysicist at the American Museum of Natural History, clearly takes great delight in his work. As he explains the intricacies of what happens when galaxies collide, a smile spreads across his face. "Astronomy is just really fun," he says. In addition to his research, Charles shares his passion for astronomy by giving public lectures, teaching university–level astronomy classes, writing popular science books and articles, and creating courses for teachers.
Charles stands in front of the Willamette meteorite, the largest found in the United States, housed in the Museum's Hall of the Universe.
Charles grew up in Ithaca, New York, where his father was a professor in the school of agriculture at Cornell. By the time he was in junior high school, even though he was involved in music, theater, and a number of other interests, he already knew he was going to be a scientist. Charles says, "There wasn't any particular event or epiphany; I just slowly came to realize that science was the right career for me." As a sophomore physics major at Harvard, Charles decided to focus on astronomy because he was eager to get involved in research as quickly as possible. "There were fewer students and more faculty in astronomy," he recalls, "so there were more opportunities for undergraduates to contribute." Unlike physics, which has been studied thoroughly for centuries, astrophysics is still a relatively wide–open field for young researchers. "There's a lot of sky, a lot of stars, and there's still so much we haven't observed," Charles points out. There are also many ways of studying the same patch of sky by observing at different wavelengths, and new technologies are constantly bringing fundamental new discoveries, making it an exciting time to do astrophysics research.
When Charles was weighing graduate schools, he decided he had had "too much exposure to non–sunny climates." So one place he considered was the University of Arizona, in Tucson, which is both home to a leading astrophysics research institution and an extraordinarily sunny place. Apart from California, Charles had never been west of the Mississippi, and he was unprepared for Arizona's stunning landscape. He recalls driving through the Sonoran Desert for the first time from Tucson to Kitt Peak National Observatory and being bowled over by the forests of towering saguaro cactuses. As he headed up Kitt Peak itself, he pulled off the road and looked out over the mountainside at the desert landscape, without a cloud in the sky, and a hawk circling below. "It was so beautiful," he says, "by the time I got back in the car I was hooked on being an observational astronomer."
The University of Arizona proved to be an excellent choice for Charles. "It was just a great, great place," recalls Charles. "The research, the environment, the faculty—they were all fantastic." At Arizona, Charles became interested in the star formation that occurs when galaxies collide. Galaxies are, in fact, colliding all the time. Says Charles, "There are a hundred billion stars coming this way, and a hundred billion stars coming that way, and when the galaxies collide they form a hundred million more."
After earning his Ph.D. in 1996, Charles worked at Kitt Peak National Observatory in Arizona for a year, then returned east and accepted a postdoctoral position at Columbia University. When he arrived at Columbia, Charles heard that the consulting company that was developing the Museum's new Hayden Planetarium and Rose Center for Earth and Space needed a science adviser. Charles jumped at the opportunity. He became fascinated by the complex process of creating museum exhibits. Besides scientific expertise, it also requires a large team of professional designers and editors whose work helps maximize the public's understanding of the material. "It was a very eye–opening experience," he says. "I worked with a lot of very talented people."
Charles hangs out with the bronze replica of Einstein by Robert Berks in the Museum's exhibition. ©AMNH, Megan Carlough
Charles was deeply involved in developing the Museum's Cosmic Pathway, a ramp representing all of time, starting with the Big Bang. As visitors walk along the spiral pathway, they traverse thirteen billion years of history, from the origin of the Universe up to the present day. "The human condition is filled with angst," Charles observes. "It's filled with all these questions: How did we get here? Where are we going? Are we alone?" He believes that having a cosmic perspective can help alleviate this angst, in some small way. The Cosmic Pathway is more than a football field long, yet all of human history falls within the width of one human hair. "It shrinks your head," Charles notes. "If you had a bad day, it's not that big a deal."
Charles's work as a consultant on the Hayden Planetarium led to his current position as an astrophysicist at the Museum, where the study of star formation and how galaxies evolve continue to be central to his research. "Galaxies are to the Universe as cells are to the human body," explains Charles. "Just as cells tell you about the nature of the body and how it functions, galaxies are crucial to understanding the nature and activity of the Universe." His research involves looking at galaxies that are forming new stars at a rapid rate, and at galaxies that once produced stars at a rapid rate but have since slowed. These galaxies can tell scientists much about how the Universe has aged.
Besides doing research, which frequently takes him back to Kitt Peak for observing runs, Charles also teaches courses at Barnard College in New York City, and for the City University of New York. But more often, his teaching involves the general public, as he gives talks to groups of students, teachers, and interns at the Museum. In these more informal settings, "I talk to more people but for fewer minutes," he says with a smile. As he points out, "An hour's worth of really cool stuff is better than a semester's worth of not so cool stuff. The question is, what do you remember?"
Charles teaches a university–level astronomy course at the Museum in collaboration with the City University of New York and funded by NASA. ©AMNH
Charles is committed to improving science education for people of all ages. In the courses he has helped develop for teachers, he encourages them to adapt and respond to their students' needs and interests. "The really important thing about teaching is to have an enthusiasm for what you're teaching and to base your teaching around the students," he says. "Your expertise, your soaring rhetoric, is always secondary to whether the students get anything out of it."
is the co–author, along with Neil de Grasse Tyson,
the director of the Hayden Planetarium, and science writer
Robert Irion, of a popular book about astronomy and astrophysics
One Universe: At Home in the Cosmos . He also writes monthly
astronomy essays for Natural History magazine under the title "Out
There." He believes that telling people about what he
has learned about the Universe is central to his role as
an astrophysicist. "I
don't make or build anything useful," Charles notes. "What
I contribute to society is knowledge and understanding. These
are things that enrich people's lives, no matter who they
are or what they do."