M. Darby Dyar, Chair of Astronomy

Professor of Astronomy and Geology

Office: Room 217 Kendade Hall
Lab: Rooms 415 c,d and 148 Clapp Laboratories
Phone: 413-538-3073, 538-3220, or 538-3240
Fax: 413-538-2239 or 538-2357


  • Ph.D. Massachusetts Institute of Technology, 1985
  • B.A. Wellesley College, 1980

Muscovite - star twinned crystal

Personal Statement

I always thought I would end up as a newspaper editor because that was my favorite activity in high school. It never occurred to me to be interested in science; there were no women science teachers, and girls did not take science courses at my high school (I hope that has changed by now!) So I first became interested in geology as a sophomore Art History major at Wellesley, when I was required to take a science course as part of the distribution requirements for graduation. In that class, I had a woman professor, Meg Thompson (Smith '70) who inspired and encouraged me. So I undertook a double major with Geology. I went immediately to graduate school at M.I.T., then to a post-doc at Caltech, and before I knew it I was in a position to help other women like myself discover the field of geology. I am the third generation of women in my family who have graduated from women's colleges, and there is not a day at Mount Holyoke when I do not reflect on how this legacy has enriched my life. I am deeply committed to the importance of educating women, especially in the sciences, and to enriching their lives through knowledge and understanding of our world (and our solar system!)

I taught at both the University of Oregon and West Chester University of Pennsylvania before coming to Mount Holyoke. My husband, Peter Crowley, teaches at Amherst College, and I have two wonderful children: Duncan, born 7/21/95, and Lindy, born 3/3/98. Mount Holyoke has an inspiring record of educating women in the sciences, and I am proud to be part of that tradition.


Courses I teach include GEO 101 (Physical Geology), GEO 104 (Planet Earth), AST/GEO 223 (Planentary Science), and AST 330 (Topics in Astrophysics: current topic: Mars). I also teach mineralogy occasionally. My goal in these courses is to give both science and non-science students an understanding of how scientists work, of the importance of logical reasoning based on available evidence, of the basic principles of earth science, and ultimately, of the interactions among humans, science, and technology. To accomplish this goal, I incorporate methods of cooperative learning by encouraging sharing of goals, resources, and tasks. My experience has been that the process of working cooperatively to solve problems results in better critical thinking by students and ultimately in better performance.

In upper division courses, the goals remain the same but with added emphasis on improving the students' facility and comfort with dimensional analysis, "back-of-the-envelope" estimations, numerical manipulations, visual and graphical representations, experimentation, and modeling. I am especially dedicated to improving ways of presenting 3-D concepts to students with differing cognitive styles; this was my motivation for designing my CD ROM and for creating my textbook, in which every illustration has an animated 3-D equivalent on its accompanying CD.



I believe that the most important goal of my research program is to involve students in the educational process of scientific thinking and problem-solving. Over the last two decades I have had the pleasure of involving more than undergraduates in my research program, of whom the majority were women; more than half have continued into graduate work in the geosciences or astronomy. These students have run my laboratory operation, conceived and performed their own research projects (including publishing and presenting the results), and assisted with nearly every piece of research done in my lab.

My research expertise involves application of the tools of physics to the problems of geology, with both terrestrial and extraterrestrial emphases. With the help of students, I currently operate one of the only Mössbauer spectroscopy labs in an earth science department in this country. My research effort depends heavily on nuclear methods (I have used the accelerators at both the University of Kentucky and the University of Guelph) and on the use of synchrotron radiation. I have pioneered the application of fast neutron activation analysis, particle-induced gamma-ray and X-ray emission techniques to the study of light elements in minerals. I am a monthly user of beam time at the National Synchrotron Light Source at Brookhaven National Laboratory, and am currently involved in development of XANES spectroscopy for microscale determinations of Fe(III)/Fe(II) in samples of geologic interest, including mantle xenoliths, crustal metapelites, lunar-analog glasses, and martian and other meteorites.

I have been interested in planetary science since graduate school, when part of my Ph.D. thesis was spent working for NASA on glasses in lunar soils. I can never forget the first time I held a lunar sample in my hand and looked up at a full moon in the sky. I find it pretty incredible that we have succeeded in getting our hands on (literally) rocks from the moon in spite of the vastness of the solar system. Since that first encounter with extraterrestrial rocks, I have remained very interested in planetary exploration. I am currently working on a large project involving planetary evolution. We are using rocks from the Earth's mantle, meteorites from Mars, lunar samples, and meteorites from an asteroid (Vesta) to try to understand how planets and their atmospheres form. Specifically, I am interested in the hydrogen contents of these rocks, and how they relate to the oxidation state of iron found in them. At the moment I am working on both lunar samples and martian meteorites. It's really neat to hold a piece of Mars in your hand!

The other focus of my research program is the study of the interaction between fluids and coexisting minerals in rocks; I seek understand how these interactions affect the mechanical behavior and physical parameters of rocks. My current work involves relating the chemistry of different types of rocks (metamorphic metapelites from western Maine, and mantle xenoliths from the S.W. U.S.) to their field relationships (in Maine) and to their strength and flow under mantle conditions (for xenoliths). My interests include fundamental questions involving the oxidation state and water/hydrogen contents of crust and mantle materials, as well as the scale and nature of the mechanisms of their transport. This approach of studying iron and hydrogen together is also critical to understanding of the mineralogy of martian soils, which is ongoing as we process data from the Pathfinder mission. One of the unresolved issues is the question of where the water that once flowed on the martian surface is now located. My work focuses on the spectral characterization of hydrogen-bearing phases and their anhydrous equivalents in meteorites, in order to assess how much hydrogen may now be stored in minerals in the martian soil vs. the hydrogen distribution that prevailed when water flowed on the surface. This problem also involves characterization of iron redox state, because of the dehydrogenation relationship H+mineral + Fe2+mineral = ½[H2]gas + Fe3+mineral.


  • Publications available in my c.v.

Planetary Science Links