Jennifer Wiseman is an astronomer who studies star forming regions of our galaxy using optical, radio, and infrared telescopes. Her career has involved oversight of national astronomical facilities as well as public science policy and discourse. In 1987 she co-discovered the periodic comet 114P/Wiseman-Skiff as an undergraduate researcher at MIT. She has a bachelor’s degree in physics from MIT, and a Ph.D. in astronomy from Harvard University. In Part 1 of this interview with ESN, she shares some of the latest astronomical findings. In Part 2 she will share how science shapes her personal life of faith.
ESN: What are the most exciting frontiers of discovery right now in your field?
JW: Well, the two hottest topics right now in astronomy are 1) the detection of planets outside our solar system (we call them exoplanets), and 2) Dark energy—which is this mysterious force that seems to be accelerating the expansion of the universe.
ESN: What’s currently happening with the discovery of Exoplanets?
JW: In the exoplanet field the technology has improved so much in the last few years, that we’ve gone from not even knowing whether there are planets outside our solar system to now having confirmed nearly 1,000 of these exoplanet systems and almost 3,000 potential candidate systems that need more study. Most of these planets have been detected through indirect means because it’s hard to take an image of a tiny planet next to a very bright star; it gets lost in the glare. Instead, astronomers have developed techniques to detect planets around stars by looking at the effects the planets have on the star. So if a planet is orbiting in front of its parent star along our line of sight, we may not be able to see the planet itself, but we can see the total amount of starlight dipping periodically with every orbit as the planet blocks our view of part of the star. That tells us a lot about the size of that planet and about its distance from the star, and it tells us about the planet’s temperature and even its density. Through this method the Kepler space telescope has detected almost 3,000 systems that are potentially planetary systems. Another way planets are found is by noticing the mutual gravitational pull between the planet and its parent star that causes the star to appear to wobble with every orbit. So measuring the wobble of stars is another way of detecting planets.
ESN: What does the future of exoplanet study look like?
JW: Our next step we hope in the coming decades is to study the atmospheres of planets around nearby stars. That will take some improvement in our technology, but we want to be able to discern whether planets that are similar to earth in size also have atmospheres like earth, and of course we’re interested to discover potentially if they could harbor signs of life. We are limited in our studies of these planets because we can only use remote sensing to study them. So we have to figure out what it is we could see in the atmospheres of these planets that would potentially be signs of life on the surface of the planet.
If we looked at Earth from a great distance we might not be able to see details like oceans and land, but rather would detect the atmosphere of the planet as a whole. And in the atmosphere we would see oxygen, which is produced by plants through photosynthesis, so that’s a clue there’s life on earth. We’d also see methane, which is largely produced by livestock. And we’d see water vapor, which in itself is not proof of life but would show the planet is habitable. We’d look for these things in the atmospheres of other planets to see if life, even simple life, is likely. Of course, we would be very excited even if that life we detected were simple life. The chances of detecting an advanced civilization are slim even if they’re out there, because of the vast distances between stars, and the delicate conditions we think are required in order to have advanced life. But that won’t stop us from looking!
ESN: Can you help us understand Dark Energy?
JW: Dark energy is a generic label put on a mystery: the mystery is why the fabric of space in which galaxies reside seems to be expanding at an accelerating pace. We’ve known for decades that space seems to be stretching. That makes it appear as if galaxies are moving apart from each other. But it was thought that eventually the expansion would slow down and maybe even reverse because gravity would eventually pull things back together again. Instead with careful measurements the last few years comparing the apparent radial motions of distant galaxies with those that are closer to us in space and time, it appears that in the last few billion years the expansion rate has actually gotten faster. What’s causing that? We don’t know, but we’re calling it dark energy. It may be some aspect of gravity that we don’t fully understand.
ESN: Do we have the technology now to discover what dark energy is?
JW: Studying dark energy is tricky because we don’t know exactly what to look for. However, we can study the effects of dark energy and how that has interacted with gravity as we understand it over the history of the universe. We do that by studying how galaxies have clustered together in the early universe as compared to now. Remember that astronomy is like a time machine. You can look back in time by looking at very distant galaxies, because it’s taken billions of years for the light to get to us from some of these distant galaxies. So we can compare the nature of these galaxies as they appeared billions of years ago to the nature of galaxies closer to us in space and time, and we can see how the composition of galaxies has changed over time. We can also see how gravity has acted over these very large scales creating distributions of galaxies in shells and honeycombed structures over the history of the universe. That tells us something about the interaction of gravity with dark energy over time.