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Computer Program Detail Page

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Stellar Aberration 3D
written by Todd Timberlake
The EJS Stellar Aberration 3D Model illustrates the phenomenon known as the aberration of starlight, first reported by James Bradley in 1729.  Aberration occurs because light has a finite speed, and thus light from a star takes a finite amount of time to travel through the tube of a telescope.  During this time, the telescope moves as a result of Earth's rotational and orbital motions (in this case, the orbital motion is more important because it is faster).  Therefore, if the telescope is pointed directly at the star the starlight will hit the sides of the tube before reaching the eyepiece.  To see the star the telescope must be pointed forward (ie in the direction of Earth's motion) very slightly.  As a result the apparent location of the star on the sky is different from its true location.

The simulation illustrates the effects of aberration for a star at any location in the sky, during any time of year.  A 3D view shows the Earth orbiting the sun, the star, and the apparent position of the star on the Celestial Sphere.  This view can also display vectors detailing how the velocity of Earth combines with the velocity of light from the star to produce a new relative velocity vector that indicates the apparent location of the star.  A separate 2D view shows the "true" location of the star as well as the apparent location for an observer looking up from Earth.

Note that some features have been simplified or exaggerated.  The Earth's orbit is treated as a circle.  The size of Earth, Sun, and Earth's orbit are greatly exaggerated compared to the distance to the star.  The speed controls allow the user to set Earth's orbital speed to an appreciable fraction of light speed, which is not realistic.  Finally, the simulation illustrates the "classical" aberration effect, not the (more correct) relativistic aberration.

Please note that this resource requires at least version 1.5 of Java (JRE).
1 source code document is available
Subjects Levels Resource Types
- Astronomy Education
= Curricula
- Fundamentals
= Properties of Light
- Historical Astronomy
= History of Astronomy
- Solar System
= Earth
- Stars
- Lower Undergraduate
- High School
- Instructional Material
= Interactive Simulation
= Simulation
Intended Users Formats Ratings
- Educators
- Learners
- General Publics
- application/java
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Access Rights:
Free access
This material is released under a GNU General Public License Version 3 license.
EJS, Easy Java Simulations, James Bradley, OSP, Open Source Physics, aberration, motion of Earth, starlight
Record Creator:
Metadata instance created May 17, 2011 by Todd Timberlake
Record Updated:
November 11, 2021 by Lyle Barbato
Last Update
when Cataloged:
May 17, 2011
Other Collections:

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Record Link
AIP Format
T. Timberlake, Computer Program STELLAR ABERRATION 3D, Version 1.0 (2011), WWW Document, (
T. Timberlake, Computer Program STELLAR ABERRATION 3D, Version 1.0 (2011), <>.
APA Format
Timberlake, T. (2011). Stellar Aberration 3D (Version 1.0) [Computer software]. Retrieved June 12, 2024, from
Chicago Format
Timberlake, Todd. "Stellar Aberration 3D." Version 1.0. (accessed 12 June 2024).
MLA Format
Timberlake, Todd. Stellar Aberration 3D. Vers. 1.0. Computer software. 2011. Java (JRE) 1.5. 12 June 2024 <>.
BibTeX Export Format
@misc{ Author = "Todd Timberlake", Title = {Stellar Aberration 3D}, Month = {May}, Year = {2011} }
Refer Export Format

%A Todd Timberlake %T Stellar Aberration 3D %D May 17, 2011 %U %O 1.0 %O application/java

EndNote Export Format

%0 Computer Program %A Timberlake, Todd %D May 17, 2011 %T Stellar Aberration 3D %7 1.0 %8 May 17, 2011 %U

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Stellar Aberration 3D:

Is Based On Easy Java Simulations Modeling and Authoring Tool

The Easy Java Simulations Modeling and Authoring Tool is needed to explore the computational model used in the Stellar Aberration 3D.

relation by Wolfgang Christian

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