Professor Spotlight: Sasselov on Super-Earths

In his new book, “The Life of Super-Earths,” astronomy professor Dimitar D. Sasselov claims that a class of planets called Super-Earths may be our best chances for finding extraterrestrial life. He draws on complementary discoveries in biology and astronomy in what he calls “an unlikely marriage.” Each spring, Sasselov teaches Science of the Physical Universe 30: “Life as a Planetary Phenomenon,” a General Education course.

The Harvard Crimson: What are Super-Earths and what makes you believe that they could contain life?

Dimitar D. Sasselov: Super-Earths are how we call a family of planets...up to two times larger and about ten times more massive than the Earth. [These kinds of] planets could have very similar environments to the ones that we’re used to here on Earth, but also be more stable over long periods of time. This potentially makes [Super-Earths] as good for habitability as our own is.

THC: If we found extraterrestrial life, do you think it would resemble humans? What would be some similarities or differences?

DDS: I’m almost certain that it’s not going to resemble us in any way. And the reason for that statement is that, first of all, even if it was based on the same chemistry...that allows for such a richness of diversity that life could go in many different directions. It will still be life, but it’s not going to resemble anything that happened here on Earth. On the other hand, if the chemistry is different, that will make it [resemble us] even less so.

THC: Are we alone in the universe? How long will it be before we find out the answer?

DDS: People quite often think of the question “Are we alone in the universe?” in terms of other civilizations out there: life forms that have reached at least our level of technological development. That question is very difficult to answer right now, but certainly if we could answer the first question, which is, “Is life on other planets possible and is it common in the universe?” then that will be a major step to answering the second one. I think that science now is progressing at the pace where within our lifetimes, we will have a pretty good answer to the first question about life on other planets.

THC: What got you interested in astronomy as a child?

DDS: I grew up in Bulgaria in a small city on the Black Sea Coast, so I was very interested in the sea, marine life, and everything related to it. But it was also a very dark place at night, so I could see the stars. And I just got very interested in it. My parents gave me a small telescope, then I built my own, and one thing led to another. So that’s how I ended up going from being a hobby astronomer to a professional astronomer.

THC: What advice would you give for students interested in astronomy?

DDS: Learn biology as well, because the future of astronomy has a lot of biology and chemistry in it. That’s the direction in which we are moving in our research. In 20 years, there will be a lot more happening at the forefront of biology on exoplanets.

—Staff writer Brian C. Zhang can be reached at brianzhang@college.harvard.edu.