The EJS Herschel's Star Gages Model illustrates William Herschel's methods of "star gages" by which he attempted to map out the shape of our galaxy in 1785. Herschel's star gages (sic) relied on two important assumptions: that Herschel's telescope (his "large 20 foot" with an 18.5 inch aperture) could see to the ends of the galaxy, and that within the galactic system stars are distributed uniformly. If the first assumption holds then the stars seen in the telescope all lie within a conical region of space with the apex at the telescope and the base at the edge of the galaxy. If the second assumption holds then the number of stars seen in the telescope is proportional to the volume of this cone. Since the volume of the cone is proportional to the cube of its height, the distance to the galactic edge in any direction is proportional to the cube root of the number of stars seen in that direction.
This simulation allows the user to use Herschel's method of star gages to map out the shape of an artificial "star system" for which Herschel's assumptions are valid. One window shows the view through a telescope, with a slider to change the telescopes direction (around a single fixed axis). Another window shows a 3D view of the star system, showing either all of the stars in the system or only those stars visible through the telescope. A third window shows a plot of the star gages. Plotting star gages for many different directions maps out a cross-section of the star system. An optional slider allows the user to decrease the distance to at which stars are no longer visible, and a menu allows the user to select a star system in which the stars are not distributed uniformly. These options let the user explore how violations of Herschel's two fundamental assumptions invalidate his star gage method.
Please note that this resource requires
at least version 1.5 of Java (JRE).
Herschel's Star Gages Activity Handout
An activity handout that guides the user through using the Herschel's Star Gages model. The activity helps the user to understand and explore Herschel's method, as well as its limitations, thereby illustrating important concepts about the nature of science. download 170kb .pdf download 235kb .doc download 9kb .tex
Published: December 15, 2011
Rights: Creative Commons Attribution-ShareAlike 3.0 Unported
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Herschel's Star Gages Source Code
A zip archive containing the Easy Java Simulations source code for the Herschel's Star Gages model. download 402kb .zip
Published: December 15, 2011
previous versions
Author: John Lattanzio
Posted: May 2, 2017 at 8:02PM
Am I doing something wrong? I get zero for counts in many directions...eg 230 to 320 degrees! There are many stars in the 3D plot but none int he telescope view. I do not have limited viewing distance turned on. John L
John, I think you may be using either the Uniform 2 or Nonuniform 2 systems from the System menu. In that case the telescope scans in a direction that is perpendicular to the plane of the star system, so you only see stars in two different directions. Just use the System menu to switch to Uniform 1 (or one of the other systems) and this problem should go away. Also, note that you can click and drag in the 3D view to get a better angle of view that will help you see what is going on. - Todd
> On May 02, 2017, John Lattanzio posted: > > Am I doing > something wrong? I get zero for counts in many directions...eg > 230 to 320 degrees! There are many stars in the 3D > plot but none int he telescope view. I do not have > limited viewing distance turned on. > John L
T. Timberlake, Computer Program HERSCHEL'S STAR GAGES, Version 1.0 (2011), WWW Document, (https://www.compadre.org/Repository/document/ServeFile.cfm?ID=11214&DocID=2261).
T. Timberlake, Computer Program HERSCHEL'S STAR GAGES, Version 1.0 (2011), <https://www.compadre.org/Repository/document/ServeFile.cfm?ID=11214&DocID=2261>.
Timberlake, T. (2011). Herschel's Star Gages (Version 1.0) [Computer software]. Retrieved December 7, 2024, from https://www.compadre.org/Repository/document/ServeFile.cfm?ID=11214&DocID=2261
Timberlake, Todd. "Herschel's Star Gages." Version 1.0. https://www.compadre.org/Repository/document/ServeFile.cfm?ID=11214&DocID=2261 (accessed 7 December 2024).
%0 Computer Program %A Timberlake, Todd %D May 22, 2011 %T Herschel's Star Gages %7 1.0 %8 May 22, 2011 %U https://www.compadre.org/Repository/document/ServeFile.cfm?ID=11214&DocID=2261
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