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Computer Program Detail Page

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Stellar Aberration 2D
written by Todd Timberlake
The Stellar Aberration 2D 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 (i.e. in the direction of Earth's motion) very slightly.

The simulation shows a telescope (depicted as a red rectangle) and a star (white point) directly overhead. When the simulation is run a pulse of light is emitted from the star and travels straight downward to Earth. The telescope moves to the right due to Earth's motion.  As a result, if the telescope is pointed straight up (ie toward the actual location of the star) the pulse of light will not reach the bottom of the telescope. Controls allow the user to set the speed of Earth and the tilt of the telescope. The user can modify the tilt until the starlight reaches the bottom of the telescope. Alternately, the user can use the Options menu to set the telescope to the correct tilt for the current speed setting.

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
- 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 2D (2011), WWW Document, (
T. Timberlake, Computer Program STELLAR ABERRATION 2D (2011), <>.
APA Format
Timberlake, T. (2011). Stellar Aberration 2D [Computer software]. Retrieved June 20, 2024, from
Chicago Format
Timberlake, Todd. "Stellar Aberration 2D." (accessed 20 June 2024).
MLA Format
Timberlake, Todd. Stellar Aberration 2D. Computer software. 2011. Java (JRE) 1.5. 20 June 2024 <>.
BibTeX Export Format
@misc{ Author = "Todd Timberlake", Title = {Stellar Aberration 2D}, Month = {May}, Year = {2011} }
Refer Export Format

%A Todd Timberlake %T Stellar Aberration 2D %D May 17, 2011 %U %O application/java

EndNote Export Format

%0 Computer Program %A Timberlake, Todd %D May 17, 2011 %T Stellar Aberration 2D %8 May 17, 2011 %U

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Stellar Aberration 2D:

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 2D.

relation by Wolfgang Christian

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