written by Mario Belloni and Todd Timberlake

The Naked Eye Sidereal and Solar Day model illustrates the difference between the sidereal and solar day. This simulation shows the view from the Earth as one would observe in the night sky. The sidereal day is the day according to the stars. It is the time it takes for a particular star to rotate around the Earth (from the Earth's perspetive) and end up in the same part of the sky as it started. On Earth, this time is 23 hours and 56 minutes. The unit of time called a solar day is the time it takes for the Sun to get back to the same place in the sky as it was before. On Earth, this time is 24 hours.

This simulation shows the difference between the sidereal and solar day by showing the motion of the stars (the zodiacal symbols) and the sun (orange). It uses an orange arrow to represent where Sun would be seen in the sky relative to the background stars. A particular star is denoted by a red arrow. Users can also add a visual of the Moon to see the difference between the sidereal month and the synodic month.

The Naked Eye Sidereal and Solar Day model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_astronomy_SiderealSolarNakedEye.jar file will run the program if Java is installed.

• Download ejs_model_SiderealSolarNakedEye.jar - 1355kb Java Archive File

Published September 2, 2013
Last Modified June 10, 2014

This file has previous versions.

This zip file contains the EJS source code for the Naked Eye: Sidereal and Solar Day model.

• Download ejs_src_SiderealSolarNakedEye.zip - 106kb Compressed File

Published September 2, 2013
Last Modified September 14, 2013

This file is included in the full-text index.
This file has previous versions.