Eclipse Simulator

Eclipse Simulator is an educational and investigative tool for finding unusual solar and lunar eclipses by combining an observing location, horizon conditions, and long-term Earth-rotation variation (ΔT). Its search catalog spans astronomical year -999 (1000 BCE) through 5000 CE. Study each event through maps, a ground-level view, and contact times.

Key features
• Search solar and lunar eclipses by date range, eclipse type, location, and other available criteria.
• Narrow the search with an observing location, solar horizon conditions near sunrise or sunset, lunar moonrise or moonset, and ΔT.
• View solar-eclipse center and limit lines, partial-eclipse regions, and lunar-eclipse visibility on Apple Maps.
• Choose an observing location and play the changing alignment of the Sun, Moon, and shadow from the ground.
• Inspect the contact times that exist for the event, including C1–C4 for solar eclipses and P1–P4/U1–U4 for lunar eclipses.
• Compare the standard ΔT model with alternative scenarios to understand how uncertainty affects historical and future timing and paths.
• View stars and constellation lines adjusted to the selected event time instead of showing today’s sky.
• Share the selected event as CSV or JSON and the displayed screen as PNG or PDF.

On iPhone, the app uses focused screen-by-screen navigation. On iPad, its wider layout keeps the catalog and event workspace within easier reach. If you grant location access, it is used only to set the observing point to your current location. You can also select a point on the map or enter coordinates.

About time and accuracy
Results are modeled values derived from the ephemeris, ΔT model, and Earth-orientation model recorded with the bundled data. The broad search catalog includes a low-precision analytical ephemeris, while the calculation provenance for a selected event is shown in the app and exports. Uncertainty remains in ΔT, future civil-time rules, polar motion, lunar-limb terrain, local terrain, and weather. Historical and future views use present-day Apple Maps and do not reconstruct borders or cities from the selected era. Lunar-eclipse color is schematic.

Use the app for education, understanding astronomical geometry, and comparing model assumptions. Do not rely on it as a guaranteed value for observation planning, navigation, scientific conclusions, or safety-critical decisions.