CNN: You've made a lot of new scientific discoveries. Which one are you most proud of and why?

Dodson-Robinson: I discovered that silicon is a particularly important element for forming planets. If you look at the stars that have planets orbiting them, they are almost all rich in silicon. That was the first big discovery I made, so I'm very proud of it. I also helped discover that some supergiant planets formed by top-down collapse, rather than bottom-up growth. It was exciting to learn that the galaxy has at least two different ways of forming planets.

CNN: What are you working on now, and what should we expect from you in the near future?

Dodson-Robinson: Right now I am working on discovering stars that formed by top-down growth, the same way supergiant planets form. My preliminary research, with my student Kevin Gullikson, indicates that top-down growth is rare among stars, but so far we have only studied a small sample of stars. We're working on putting together a bigger set of stars to study -- 300 or so -- to finally answer the question, how common is top-down star and planet growth?

CNN: How would you define 'planet'?

Dodson-Robinson: "What is a planet?" seems like it should be an easy question, but it's not. The International Astronomical Union voted on the definition of a planet in 2006. It's a spherical body that's large enough to be the dynamically dominant member of its orbit (meaning it doesn't share an orbit with other similar-size bodies), but small enough not to burn deuterium (heavy hydrogen) in its interior.

Since I study planet formation, I favor a slightly different definition. A planet is any dynamically dominant member of its orbit that grew from the bottom up, starting with dust grains colliding to form pebbles. If such an object gets large enough to burn deuterium (about 13 Jupiter masses), it should still be called a planet. Stars and brown dwarfs form from collapsing gas clouds or disks in quite a different process.

Are you involved in any volunteer work?

I made up an interactive activity called "Cassini Collage," where I show pictures of Saturn and its moons taken by the Cassini spacecraft and the audience uses the pictures to figure out whether Saturn has seasons, why its icy moons have cracked surfaces and how Saturn's rings are sculpted. I have done my Cassini Collage activity for UT's first-year honor students and for a Unitarian fellowship. I have done other presentations about planets for student clubs and groups of retirees.

What advice would you give people interested in pursuing a degree in science?

There are lots of things you can do with a degree in science. It's a good starting point for many different careers, a lot of which involve making new discoveries. If you want to keep on learning all your life, then being a scientist is a great career choice.