written by Wolfgang Christian, Todd Timberlake, and Mario Belloni

The Solar and Lunar Eclipse JavaScript Model simulates the occurrences of solar and lunar eclipses. Moon's orbital inclination of 5.145 degrees with respect to the ecliptic (the Earth-Sun orbital plane) is what is responsible for solar and lunar eclipses not occurring every month. In addition, the orbital plane of Moon precesses every 8.85 years, the so-called precession of the apsides. The inclination and the motion of Moon and Earth are depicted (the size of Sun, Earth, and Moon and the size of Moon's orbit are not shown to scale). The illuminated sides of Earth and Moon and the regions of possible eclipses (in yellow and green) are also depicted. In the Sky View, the motion of Sun and Moon across the sky (+/- 7 degrees from the ecliptic) are shown. Moon's phase is shown and solar and lunar eclipses can occur on the ecliptic when Earth, Sun, and Moon line up properly.  

The Solar and Lunar Eclipse JavaScript Model was developed using the Easy Java/JavaScript Simulations (EJS) modeling tool. Although EJS is a Java program, EJS v5 and above can be used to create stand-alone JavaScript programs that run in almost any browser.

• Download ejss_model_SolarLunarEclipse.zip - 919kb Compressed File

Published May 13, 2017
Last Modified June 29, 2017

This file has previous versions.

Solar and Lunar Eclipse model packaged as a stand-alone Android App. Requires Android 6 or above and fast processor for 3D WebGL.

• Download CelestialSphere.apk - 4576kb application/octet-stream

Last Modified July 20, 2017

This file has previous versions.

A student worksheet for the Phases of the Moon and the Solar and Lunar Eclipses simulations.

• Download PhasesEclipsesWorksheet.pdf - 119kb Adobe PDF Document

Published May 20, 2017
Last Modified May 27, 2017

This file is included in the full-text index.

JavaScript Easy Java Simulations source code.  Requires EJS.

• Download ejss_src_SolarLunarEclipse.zip - 408kb Compressed File

Last Modified December 23, 2020