"I would recommend this program for high school students in such classes as astronomy or advanced physics. This program could be used as a visual aid for lower leveled science, however I believe that in order to actually comprehend this program, students should have some background in the forces at work. A general physics course wouldn't really delve into astrophysics as much as a higher level physics course such as AP Physics. This program is perfect for mid year astronomy students though.
"This program meets the NSES science and technology content standard E, and will facilitate further the development of content standard D by allowing students to see how the galaxies in the universe came to be what we know them to be. Additionally, the resource meets NJSES standards 5.7 A and B and 5.9 A, B, C, and D.
"The cost of the resource is free, as software for both Windows and Macintosh are freely downloadable and can be installed on an unlimited number of machines.
"The software does require that users be able to manipulate a mouse and be able to see the computer screen. The primary use of the software is the real-time visualization and manipulation of a gravitational dynamics model.
"The software allows students to see complex concepts in gravitational dynamics, allowing visual learners to explore concepts in gravity and angular momentum. Additionally, the ability to manipulate the visualization by flipping and spinning it will help make the material more accessible to tactile/kinesthetic learners. This activity allows for real user interaction and address the needs of multiple learning styles. It includes activities that are within the students' everyday experience, such as linking the orbit of the Earth around the Sun to the length of the year, and should allow for an engaging student experience.
"The lesson plans bundled with the software include a case in which a galaxy at "rest" is allowed to collapse, and at the point of collapse the galaxy is seen to rebound. Care must be taken in showing this to students, as if a large star size is used it is not immediately apparent to students that the bulk of the galaxy is, in fact, in a collapsed state at the center of the original mass.
"Additionally, when too large of a time step or too small of a shield radius is used, errors quickly make the results unusable, and can lead to misconceptions by students. A common misconception in using a model with a very large central mass is that students misrepresent the error in the program where forces near the center are over estimated resulting in the false result of the ejection of stars from the galaxy as the effect of a "black hole". In general, much care must be taken with students to make them understand the assumptions and limitations of the software - that this treats objects as non interacting point masses, that numerical error occurs for very large masses, very large timesteps, or an inappropriate value for the shield radius.
"For the Macintosh program, the software downloaded and opened properly.
There were some minor difficulties in that the software opened without
any default galaxy file, and some instruction on how to start a new
model would have been useful. Editing the galaxy was difficult due to
the need to restart the galaxy after any change. It is difficult to
distinguish individual stars when the trace option is activated. A
possible solution to this would be to give the user an option to change
the color of the trace from the stars, so instead of having to
distinguish individual red stars on a red background, it might be a
possibility to allow for red stars with a green trace so the current
position of the stars can be separated from the past position of the
stars. Although I find the help menu helpful for the over all program,
it is lacking in a few minor areas such as: Additional options of "View"
(tails, red shift, depth cueing, etc.), and "Action" (mainly wobble and
rotate z axis). I also found the help balloon action less then helpful.
It appeared that for everything I wanted help on there wasn't a help
balloon, and for everything I didn't need help on there were several help
balloons. Over all I would say this is a good tool, but if I had the
option I would recommend the windows version instead, however there are
some things I believe that can be changed about the windows version as well.
"For the windows version, it was difficult to determine the proper
download link for the software. Currently the download link is far down
on the page, below page graphics, and it is necessary to scroll down to
find the link. I found that the online help menu is actually customized
for the power Mac program, however the help document that comes with the
software is set up for both Mac and PC. This is only minor since the
only difference is in the fact that the online help menu refers to the
step by step setup as "down load the software onto you Power Mac." The
help menu available through the actual GalaxSee program needs a lot of
work. I suggest you make the tutorial available through the help menu
since that is where I would expect to find it. The tutorial is much
better than the Mac version, however it also doesn't address the "View"
options.