Chasing Asteroid Occultations for Adventure and Science

Come join us for our monthly Astronomy talk!
7:30pm-8pm: Social time with snacks
8pm: Talk begins

Title: Chasing Asteroid Occultations for Adventure and Science

Abstract: Asteroids are a rapidly emerging field of importance in Astronomy. With the release now of the GAIA Mission high precision astrometry of both stars and asteroids, it is now possible for citizen astronomers to get data that permits more accurate astrometry than the most powerful telescopes. Asteroids’ slow orbital motion, and our ability to GPS time stamp high speed video frames, we can pin down not only their centroid position, but the detailed shape and presence of possible moons of these objects. Kepler’s 3rd Law then permits measuring directly their bulk density, putting tight constraints on their composition. What are they made of? Surface reflection only gives clues of surface composition, not their bulk characteristics. What is their formation history? Collisional? Slow accretion? Astronomer Richard Nolthenius is one of the most prolific and long time gatherers of the raw data for these questions, and with equipment easily accessible to dedicated amateur astronomers, thanks to the volunteer efforts of members of the International Occultation Timing Association. He will share his experiences, the gear needed, and highlights of the asteroid adventures he’s organized for his growing team of fellow ‘roid chasers in Santa Cruz.

Bio: Richard Nolthenius (Rick, to his Cabrillo College students), has been an active astronomer for 50 years. He got his B.S. Honors in Mathematics from the University of Arizona in 1975, Masters in Aerospace Engineering from the same University in 1976, worked as a thermodynamics analyst and designer for General Dynamics’ Convair Space Division in San Diego, returned to earn a PhD in Astrophysics at Stanford and finishing at UCLA in 1984, a post-doctoral fellowship at Steward Observatory, and eventually decided to settle in Santa Cruz where he pursued astronomy research at UC Santa Cruz as a visiting researcher and lecturer while holding the Dept of Astronomy Chair position at neighboring Cabrillo College. In the past 4 years, he’s added a position at the new Earth Futures Institute at UC Santa Cruz under long-time collaborator and co-author Sandra Faber. His research interests have ranged widely, from chaos theory applied to barred galaxies, application of the new technique of Smoothed Particle Hydrodynamics to black hole tidal fields, using planetary nebulae as dynamical probes to map galaxy rotation curves, galaxy clustering as a diagnostic of the nature of Dark Matter with Joel Primack, and during the past decade, the Thermodynamics of Civilization and its application to prospects for our climate future. During these many years, he’s long been an active observer, first of lunar occultations, and then on to asteroid occultations. In 2024 he observed, reduced, and submitted his data on 91 successful asteroid occultations, and 34 so far in 2025. Rich has been author or contributing co-author on dozens of papers written from these efforts.

About the event:

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