Eclipse chasing is the practice of traveling to specific geographic locations to observe solar eclipses, particularly total solar eclipses. Individuals who engage in this activity are commonly referred to as eclipse chasers or umbraphiles (from the Latin umbra, meaning shadow, and Greek philos, meaning loving).
Motivations and Culture The primary motivation is the observation of totality—the brief period during a total solar eclipse when the Moon completely covers the Sun's disk, revealing the solar corona, prominences, and chromosphere. This phenomenon is visible only within a narrow path on the Earth's surface (the path of totality), typically ranging from 100 to 250 kilometers in width. Because the path of totality for any given eclipse covers a small fraction of the Earth's surface, observing multiple total eclipses usually requires significant travel, often to remote or international destinations.
Eclipse chasing has developed a distinct subculture with dedicated websites, mailing lists, conventions, and tour operators specializing in eclipse expeditions. Veteran chasers often track their "totality count" (the number of total eclipses successfully observed) and cumulative time spent in totality.
Logistics and Planning Planning for an eclipse expedition typically begins years in advance. Key factors include:
- Weather prospects: Climatological data is analyzed to select locations with the highest probability of clear skies during the eclipse month.
- Accessibility: Transportation infrastructure, accommodation availability, and political stability of the host region.
- Duration of totality: Locations near the centerline of the path offer the longest duration of totality (maximum theoretical duration is approximately 7 minutes 32 seconds, though typical durations are 2–4 minutes).
- Equipment: Chasers often employ specialized photographic equipment, including telescopes with solar filters, dedicated solar cameras, and automated tracking mounts to capture the phases of the eclipse.
Scientific and Citizen Science Contributions While many chasers are amateurs, the community contributes to scientific research through citizen science initiatives. Organized efforts have included:
- Measuring the solar diameter and shape via timings of Baily's beads.
- Monitoring coronal dynamics and polarization.
- Recording shadow band phenomena.
- Participating in projects such as the Citizen CATE (Continental-America Telescopic Eclipse) Experiment and the Eclipse Megamovie Project, which aggregate images from multiple sites along the path to create extended datasets of coronal evolution.
Historical Context Organized eclipse expeditions date back to the 19th century, often funded by governments or scientific academies (e.g., the 1919 Eddington expedition which tested general relativity). The modern hobbyist phenomenon expanded significantly in the late 20th century with the advent of commercial jet travel, accurate eclipse predictions (notably Fred Espenak's "Fifty Year Canon of Solar Eclipses" and NASA's Five Millennium Canon), and the internet, which facilitated information sharing and logistics coordination.
Safety A critical aspect of eclipse chasing is eye safety. Observers must use certified solar filters (compliant with ISO 12312-2) during all partial phases. It is only safe to view the Sun without filtration during the brief seconds of totality. Failure to use proper protection can result in permanent retinal damage (solar retinopathy).
