A few thousand stars are visible to the unaided human eye--if you are at a dark site. Today, about a billion stars have been cataloged by astronomers, and we deduce that hundreds of billions of stars exist in our Galaxy. In turn, we know that the Milky Way is just one of hundreds of billions of galaxies in the observable universe. Applying the tools of physics, chemistry, mathematics, and computer science, we aim to understand the formation, evolution, interactions, and ultimate fate of stars and galaxies. New technologies now allow planets around stars to be detected, allowing us to finally measure their properties instead of merely guess at them.

The pictures above are an artist's (Dr. Robert Hurt) visualization to scale of what we believe the Sun, a very-low-mass (M9 dwarf) star, an L-type brown dwarf, a T-type brown dwarf, and the planet Jupiter would look like if we could line them all up. It's odd but true that the smallest stars, the largest planets, and the brown dwarfs in between are all about the same size even though the star is eighty times more massive than Jupiter! The picture below is an artist's (Rob Gizis) concept of the L1 dwarf star WISEP J190648.47+401106.8. Using the Kepler space telescope and Gemini-North telescope, I led a team that observed powerful white lights for the first time on this type of star.

As a faculty member at the University of Delaware, I aim to advance the frontiers of scientific knowledge, to communicate what and how we have learned to students, and to train new scientists so that "the immense advances in science" continue in the next generation. You can check out my detailed John Gizis CV or check the links at the left to see more of my activities.

My office is Room 236 in Sharp Lab. You can write me at 104 The Green, Newark DE 19716, but I recommend e-mailing me at gizis@udel.edu.


I am an observational astronomer who is primarily interested in very-low-mass stars and brown dwarfs. These objects can emit photons over most of the electromagnetic spectrum, so many different telescopes are necessary to measure their properties. My projects have made use of X-Ray (NASA's Chandra Telescope), optical (Kepler/K2, Hubble), near-infrared (JWST, 2MASS, IRTF) and mid-infrared (Spitzer Space Telescope, WISE, Herschel) telescopes. I am proud to be contributing to the LSST project as a member of the Differential Astrometry Working Group, Commissioning Astrometric Calbration Science Unit and former co-chair of the Vera C. Rubin Observatory LSST Stars, Milky Way and Local Volume Science Collaboration Team. You can find more details at my research page.


One of the pleasures of being in a Physics and Astronomy department is the opportunity to teach a great variety of courses. In Fall 2023, I'm teaching PHYS133 Introduction to Astronomy. In Spring 2024, I'm teaching PHYS333 Fundamentals of Astrophysics


I am currently Associate Director of the UD Data Science Institute. I am a member of the Steering Committee of the UD AAUP chapter For fellow astronomers, I am a member of the HREF="https://aas.org/capp-strategic-plan">American Astronomical Society's Committee on Astronomy and Public Policy (CAPP) and am on the Board of Directors for Mount Cuba Astronomical Observatory. I organized BDEXOCON, a conference about brown dwarfs and exoplanets, which was held at UD in 2014, 2017, and 2019 -- and we hope to hold it again soon.