In this occasional series, we ask instructors to discuss how they engage students in the great questions of our time.
Q. In a nutshell, what is this class about?
A. In recent years thousands of planets have been found orbiting distant stars. So, the big question is: “is there life outside of our solar system?” There is a new science in astronomy that is called astrobiology which investigates where in the Universe life could develop and evolve. In this class, we’re explaining the methods of astrobiology, and trying to figure out where life might exist in the universe. We do this by first looking at how life has evolved and functions here on Earth, and we then examine the conditions that make life possible and see where else life might exist or survive.
Q. What are some goals you set for your students?
A. I first want the students to develop an awareness of what makes our own planet special. We’re always wondering “Well, there’s life on planet earth, but why is there life on Earth in the first place?” There are many reasons why life exists on our planet, many conditions that must be met: the specific location of our planet in our solar system, the size and internal structure of the Earth, it’s ocean and atmosphere, all things that contribute to make life possible. I want students to understand this close relationship between the structure or geology of the Earth, and the fact that there is life on it.
Another thing I want students to understand is that life is likely to be very common in the universe. We now know there must be billions of planets like Earth, just in our own Milky Way. Because the laws of Physics are the same everywhere and geological and biological processes are universal, life should always spontaneously appear, given the proper conditions are met. Students should also be in awe at the scale of the Universe, both in space and in time. Life does not sprout easily, and it takes a lot of time to evolve intelligent creatures like us, but the universe is very patient, it’s got all the time in the world! Yes, life perhaps is rare, but the universe is also incredibly vast, and there are so many planets and stars that it is very unlikely that we are alone.
Q. Which aspects of your class do you think your students find most interesting?
A. I hope they enjoy when we speculate about what extraterrestrials might look like, and how very different they may be from us. The really cool part of the class is near the end when we think about space travel — how we could travel to other stars and maybe even colonize them — and the concept of extraterrestrial civilizations. While astrobiologists are pretty sure there must be life in the Universe, at least simple life like bacteria, that does not necessarily mean there is intelligent life. However we can use mathematics and a bit of speculation to calculate the number of intelligent civilizations there might be in our galaxy, which is a very intriguing thought and a lot of fun because even astrobiologists don’t really agree on the answer.
Q. What can students expect to get out of this class?
A. I hope they get the idea that although we haven’t yet found any life elsewhere in the universe, any signs of other intelligent civilizations, or any credible signs of extraterrestrials visiting our planet, it remains extremely likely there is some extraterrestrial life somewhere just waiting to be found. I want students to gain a sense of perspective about our own human existence, knowing that life here on Earth is not unique. I’m hoping this will also motivate them to remain curious about science in general, and astronomy in particular, especially knowing that it’s very possible that in the next few decades, we’re actually going to find definitive proof of life in another star system. But to truly believe it when it happens, you need to know at least a little bit how science works and have the tools to differentiate between what is real science and what is not.
Q. How did you become interested in teaching this subject?
A. I’ve always been in interested in this topic as far as I remember. When I was working on my dissertation as a graduate student, I got interested in knowing the location of stars nearest to our Sun. There were no extrasolar planets known at the time. The first one around another star like our Sun was discovered in 1995, and after that in the late ‘90s and early 2000s there were a slew of extrasolar planets discovered. So many of them were discovered that this got me really excited about the idea of extraterrestrial life. It was starting to feel very real.
Q. What’s the most unique — or challenging — assignment that you give to students in this class?
A. One assignment that we do is challenging because it involves using statistics. It is the Drake equation, which calculates how many intelligent civilizations there are in the galaxy. Because there is not just one valid answer, you must calculate it for yourself using your own assumptions. There’s a lot of guessing that comes into it because you must estimate things like how many planets you think every star has and the probability of life on any one planet. It’s a bit challenging, but it’s a fun exercise because no one comes to exactly the same answer, and it always opens up a debate about whether we might get visited one day or if we might find friends or foes somewhere out there in the vastness of the galaxy.