Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Physics (PhD)

Administrative Home Department

Department of Physics

Advisor 1

Robert J Nemiroff

Advisor 2

Jennifer L Bartlett

Committee Member 1

Brian E Fick

Committee Member 2

James L Hilton

Committee Member 3

Claudio Mazzoleni


The standard value for atmospheric refraction on the horizon of 34', used in all publicly available sunrise and sunset calculators, is found to be inadequate. The assumptions behind atmospheric models that predict this value fail to account for real meteorological conditions. The result is an uncertainty of one to five minutes in sunrise and sunset predictions at mid-latitudes (0° - 55° N/S). A sunrise/set calculator that interchanges the refraction component by varying the refraction model was developed. Two atmospheric refraction models of increasing complexity were tested along with the standard value. The predictions were compared with data sets of observed rise/set times taken from Mount Wilson Observatory in California, University of Alberta in Edmonton, Alberta, observations from various locations in Chile, and on-board the SS James Fergus in the Atlantic Ocean. Increasing the complexity of the model did not yield significantly better results. These observations make up the entirety of documented sunrise and sunset times. A thorough investigation of the problem requires a more substantial data set of observed rise/set times and corresponding meteorological data from around the world. A mobile application, Sunrise & Sunset Observer, was developed so that anyone can capture this astronomical and meteorological data using their smartphone as part of a citizen science project. Data analysis will lead to more complete models that will provide higher accuracy rise/set predictions to benefit astronomers, navigators, and outdoorsmen everywhere.