stroGrav is an astronomy software program that allows you to simulate how astronomical objects move and interact under the force of gravity. It features superb interactive 3D graphics which allow you to move around within a many-body astronomical system, while watching how it evolves with the passage of time.
A wide variety of sample files are provided, including Solar System, space mission, and abstract systems, and these enable you to experiment with the astronomy software without having to enter your own data. The comprehensive editing facilities allow you to either create your own astronomical systems, or to modify existing ones, and provide you with an almost endless scope for experimentation and investigation.
AstroGrav can be used to visualize and understand the following aspects of gravitational systems and astronomical systems.
* Basic concepts of mass, position, velocity, acceleration, force, momentum, and energy.
* Kepler's Laws of Planetary Motion and Newton's Law of Gravitation.
* Many body systems and the n-body problem.
* Orbits and Lagrange points.
* Interchange of potential energy and kinetic energy in gravitational systems.
* Projectiles and escape velocities.
* Gravitational slingshots used in space missions.
Newton's Law of Gravitation
AstroGrav calculates how astronomical objects move according to Newton's Law of Gravitation, and displays the results as they are calculated so that you can watch the system evolve as in a movie. The astronomy software is very accurate, dynamically calculates orbits as a system evolves, deals correctly with object collisions, and can cope simultaneously with objects on many different timescales.
AstroGrav is ideal for any of the following.
* Astronomers interested in studying the evolution of gravitational systems.
* Teachers and educationalists seeking to deliver courses on math, physics, or astronomy.
* Students of math, physics, or astronomy.
* Anyone else interested in studying how objects move and interact under the force of gravity.
Interactive 3D Animated Graphics
AstroGrav has superb interactive 3D animated graphics, in the form of view windows. View windows let you view a simulation in the form of a three-dimensional model which you can manipulate and navigate around, while watching the simulation evolve with the passage of time. The phases of non-luminous objects (planets, moons, asteroids, etc) are correctly displayed, and you can even attach your viewpoint to an object so that you can watch the evolution of the simulation from the object's point of view.
View windows also allow you to do the following.
* Display the distance, speed, magnitude, and phase of selected objects.
* Display the angles between objects.
* Change the magnification and brightness of the window.
* Show or hide the names of objects.
* Show or hide the velocities of objects.
* Show or hide the accelerations of objects.
* Show or hide the orbits of objects.
* Show or hide the coordinate axes.
You can have several view windows displayed at once, so that you can (for example) use one window to view the entire systen, another to view a close-up of an area of interest, and a third to view the system from the viewpoint of a particular object.
Other Ways of Viewing a Simulation
In addition to view windows, AstroGrav allows you to view a simulation as a table of data, a tree showing the object hierarchy, or as details of any desired object.
Table windows let you view a simulation in the form of a table, with each object's data occupying one row of the table. AstroGrav keeps track of a large number of numerical parameters for each object in a simulation, and these are divided into six groups. Table windows allow you to select any combination of groups for display, and to sort the data on any desired column. You can also change the column widths, reorganize the columns, and change the row heights.
Structure windows let you view a simulation in the form of a tree showing the hierarchical structure of the system. This allows you to easily see how the objects in a simulation are organized. The nodes of a tree can be opened or closed at will in order to focus on any particular area of interest.
Object windows let you view a simulation by showing all the details of a single object, including its relationship with the other objects in the system. The numerical parameters are divided into the same six groups as in table windows, with all six groups always being displayed. In addition to the numerical data, two trees are also shown - one showing the object's family, and the other showing what the object is orbiting. These two trees can be manipulated in the same way as the trees in structure windows.
Dynamic Calculation of Object Orbits
AstroGrav dynamically calculates the instantaneous orbits (also known as osculating orbits) of objects as a simulation evolves. The display of orbits in view windows helps you to visualize the three-dimensional structure of a simulation, and the numerical values of the orbital parameters are displayed in table windows and object windows. Watching how the orbits change as a simulation evolves allows you to study how the interactions between objects alter and distort the objects' orbits.
Comprehensive Editing Facilities
AstroGrav provides a comprehensive range of editing facilities for setting up and modifying your own simulations. These facilities allow you to add, remove, and modify single objects, and there is also a facility for adding entire families of objects. You can edit the date/time of a simulation, modify the units used to express physical quantities, and add notes to a simulation in order to keep a record of how the simulation was created, and how it is to be used. A sophisticated undo/redo facility is also provided to allow you to undo and redo as many changes as you like.
Illustrative Sample Simulations
A wide variety of sample simulations are provided, and these enable you to experiment with AstroGrav without having to go to the trouble of creating your own simulations. These sample simulations include Solar System simulations, space mission simulations, and abstract simulations, as a well as a simulation specially provided for use with the tutorial. Each sample simulation has accompanying notes explaining what the simulation is and what you can do with it.
Documentation and Tutorial
AstroGrav comes complete with full documentation that includes a comprehensive beginners' tutorial.
The AstroGrav documentation is organized into sections and subsections, with links within the pages that allow you to move easily around from page to page. It contains the tutorial, explains in detail how to use the different types of windows, explains the various numerical quantities that are used to describe an object, and explains each of the many menu items. In the unlikely event that you are unable to find the solution to a problem in the documentation, our email support is available to you for help and advice.
The AstroGrav tutorial contains several simple exercises that will introduce you to the basic features of AstroGrav, and show you how to use them effectively. Each exercise leads you step by step through the stages necessary to achieve the desired objective. You will quickly learn how to open existing simulations, evolve simulations, and use the different types of AstroGrav windows. In later exercises, you will learn how to edit existing objects, add new objects, and add new families of objects. After completing the exercises, you will have all the skills needed to use AstroGrav on your own.
600 MHz Intel Pentium III processor or equivalent, 128 MB RAM, 50 MB disk space