Discovering Atmospheres, Rings, and Small Bodies with Occultations
By Dr. Eliot Young

Is the subject of this month’s Estes Valley Astronomical Society (EVAS) meeting. EVAS, in conjunction with The Estes Park Memorial Observatory, is offering a free public open house and lecture on Saturday, March 28th at 7:00 pm. The goal of EVAS is to promote amateur astronomy and education in the Estes Valley.

An artist’s concept of an asteroid occulting a very bright star as seen from close up. NASA / ESA / Greg Bacon (STScI).

Solar system bodies occasionally pass in front of stars. These events are called occultations, and there is a rich legacy of discoveries from occultation observations. Pluto’s atmosphere, the Uranian ring system, and the contact-binary nature of Arrokoth were all discovered from occultations. If the occulted star is bright enough, occultations can provide extraordinary spatial resolutions, potentially retrieving the vertical structure of atmospheres or the radial structure of rings at scales of a few hundred meters.

Predicting occultations has become much more reliable since the Gaia mission released star positions at the 24-microarcsecond level. This presentation will cover the basics of occultation predictions and some of the practical points of observing occultations. We’ll discuss how light is refracted through atmospheres, what causes central flashes, and what we can learn from cases that resolve diffraction features. We’ll look at a few cases in detail, like the 2022 occultation by Titan, in which Titan’s disk was resolved by the adaptive optics systems at the Keck and Gemini observatories.

Dr. Elliot Young

Our speaker is Dr. Eliot Young, a Boulder-based planetary scientist and Senior Project Manager at the Southwest Research Institute. He has a physics degree from Amherst College and a Sc.D. from M.I.T. in Earth, Atmospheric, and Planetary Sciences. His areas of research include observing the atmospheres of Venus, Titan, and Pluto, as well as developing telescopes for high-altitude balloons. He has organized occultation observing campaigns on five continents. He is also a master’s age-class champion in alpine skiing and a race coach at Eldora Mountain Resort.

The meeting is scheduled for Saturday, March 28th, at the observatory (MAP). The observatory is just north of the high school at 1600 Manford Ave. Park in the teacher’s parking lot between the high school and the observatory.  The doors will open at 7:00 pm, and the meeting will start at 7:30 pm.  The presentation, including a question-and-answer period, lasts about an hour. After the presentation, weather permitting, we will look through our 16-inch dome telescope at various celestial objects.