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CONVERSATIONS WITH SCIENTISTS

Jean-Luc-Margot: Redefining a Planet

John-Luc Margot

UCLA

[The biggest misconception is the] "myth that there are 'other ways of knowing' that can compete with the scientific method—the scientific method is by far the best tool at our disposal for approaching the truth."

Jean-Luc Margot is a professor at the University of California, Los Angeles (UCLA) in the department of physics and astronomy, and the department of earth, planetary and space sciences. Born in Belgium about 20 miles east of Brussels, Margot earned a bachelor's degree in electrical engineering from the Université Catholique de Louvain in 1993. He continued his education in the U.S., completing a Ph.D. in astronomy and space sciences at Cornell University in Ithaca, New York in 1999, followed by two 2-year postdoctoral fellowships, first at the Arecibo Observatory in Puerto Rico, and then at the California Institute of Technology (Caltech) in Pasadena. From 2004 to 2008, Margot taught astronomy at Cornell before relocating to Los Angeles to join the UCLA faculty.

Margot is the recipient of numerous awards and research grants, most recently from NASA and the National Science Foundation. He is widely published and is active in public outreach programs, including lectures, media interviews, conference presentations and entertainment industry consultations.

Margot's research focuses on the formation and evolution of planets. His research group concentrates on two main areas: The "physical and dynamical characterization of near-Earth objects, primarily with . . . radar astronomy" and the "investigation of planetary interior properties and processes from high-precision measurements of spin and orbital dynamic."

Below are Jean-Luc Margot's February 10, 2016 responses to questions posed to him by Today's Science. Some of the questions deal with how he became interested in science and began his career in astronomy, while others address particular issues raised by the research discussed in How to Define a Planet.

Q. When did you realize you wanted to become a scientist?

A. I was tinkering with physics demos at a young age, and I took as much math and science as I could in grades 7-12. The conscious realization that I would go into science or engineering at the Ph.D. level probably came during grade 11 or 12.

Q. Are there particular scientists, whether you know them in person or not, that you find inspiring?

A. I had the pleasure of meeting Carl Sagan while I was a graduate student at Cornell University. He inspired me because he was a top-notch scientist who was leading a research group and actively publishing in peer-reviewed journals while doing the best public outreach that I have ever seen.

Q. What do you think is the biggest misconception about your profession?

A. There are so many. The myth that professors at research universities have "summers off" — summers are devoted to full-time research. The myth that universities pay for conference travel — scientists pay for these expenses through grants that are awarded competitively. The myth that telescope facilities can generate revenues — telescopes are nonprofit operations whose budgets come primarily from federal agencies or philanthropy. The myth that scientists are engaged in propaganda with respect to climate change to realize a financial gain — scientists would be studying the climate whether humans are interfering with it or not, and they are not making more money because climate change exists. The myth that evolution is "just a theory" — the existence of biological evolution is a fact. The myth that scientists have evidence for UFOs and are conspiring to hide it — scientists would fight for the privilege of announcing such an important discovery. The myth that there are "other ways of knowing" that can compete with the scientific method — the scientific method is by far the best tool at our disposal for approaching the truth.

Q. Your definition of a planet, if I understand correctly, uses a ratio involving several parameters — star mass, mass of the star-orbiting body, orbital period. Why did you dub this ratio Pi?

A. I use the upper case "Pi", not the lower case "pi". It comes from the Greek word for planet ("wanderer; something that moves"), which starts with the letter Pi.

Q. In the Solar System, the planets fall into two broad categories — smaller rocky planets and gas giants. Do these two categories register differently on your ratio — that is, do planets like Earth, Mars and Venus have lower values, say, than Jupiter, Saturn and Neptune, or do the values they generate not correlate with whether they are rocky?

A. The Pi values of Uranus and Neptune are comparable to those of the terrestrial planets, so Pi is unrelated to composition.

Q. Has the process of coming up with this definition of a planet caused you to look at any astronomical questions or findings in a new way? Has it raised any questions for you?

Planet Orbit Clearing Criteria

Jean-Luc Margot/Shutterstock

"The criterion splits Solar System bodies into two very distinct classes. Planets and non-planets differ in their Pi values by an enormous factor (about 1,000). This difference is almost certainly related to how these distinct classes of bodies formed and evolved."

A. The criterion splits Solar System bodies into two very distinct classes. Planets and non-planets differ in their Pi values by an enormous factor (about 1,000). This difference is almost certainly related to how these distinct classes of bodies formed and evolved. So the criterion has raised additional questions about the process of planet formation and evolution.

Q. Your Pi ratio involves three parameters that are, in principle, not too difficult for astronomers to measure for star systems reasonably close to us. Are there any other parameters that you think would have been useful to measure if they had been more accessible to observation?

A. We know that these three parameters are easy to measure because they have been measured already for 99% of all known exoplanets! It's only a matter of time before we obtain measurements for the remaining 1%. The criterion works for nearby stars but it also works for distant stars. One exoplanet that has been classified with the criterion is 21,500 light years away from Earth (the entire galaxy is 100,000 light years across). As long as we can measure the three required quantities, there is no limit to how far we can go.

The three parameters are necessary and sufficient to classify planetary bodies — other parameters are neither necessary nor useful. We probably would love to know what these planets look like, but that is irrelevant for the classification. For instance, all the planets in the Solar System (except Earth) were declared planets long before we had any idea of what they looked like.

Q. Where do you spend most of your workday? Who are the people you work with?

A. At UCLA. I work most closely with UCLA postdocs, graduate students and undergraduate students. I also have collaborators at other institutions.

Q. What do you find most rewarding about your job? What do you find most challenging about your job?

A. The most rewarding aspect of the job is to assist others in their training and career development. There is also the occasional discovery or high-precision measurement that brings satisfaction.

The most challenging aspect of the job is to manage funding for my research group, especially for students who have research interests in areas considered unconventional, because most funding agencies will not fund work that is considered unconventional.

Q. What has been the most exciting development in your field in the last 20 years? What do you think will be the most exciting development in your field in the next 20 years?

Kepler Space Telescope

NASA

"The Kepler Space Telescope was the biggest game-changer in astronomy in my entire life, and perhaps in the history of astronomy since Galileo."

A. The Kepler Space Telescope was the biggest game-changer in astronomy in my entire life, and perhaps in the history of astronomy since Galileo. [See Kepler's "Beautiful Data", March 2011; Kepler Strikes Planetary Pay Dirt, January 2011.]

In the next 20 years, there is a nonzero chance that we will detect signals from an advanced civilization. This discovery would change everything.

Q. How does the research in your field affect our daily lives?

A. Calculus was invented to figure out the motion of planets. Calculus made airplane travel and cell phones possible. Today's scientific investigations are making tomorrow's inventions possible.

Q. For young people interested in pursuing a career in science, what are some helpful things to do in school? What are some helpful things to do outside of school?

A. In school: Math. English. Outside school: Character-building experiences.

Citation Information

Jean-Luc-Margot: Redefining a Planet.” Today's Science, Infobase Learning, Feb. 2016, http://tsof.infobaselearning.com/recordurl.aspx?ID=34750. Accessed 23 Oct. 2018.

Record URL: http://tsof.infobaselearning.com/recordurl.aspx?ID=34750