Figure 9 is a screen grab from the running applet. To try this virtual experiment, select the ATLAS icon to start the applet.

See the list of other virtual experiments.

VIRTUAL EXPERIMENT 1
Take a Spin Around the Neighbourhood

• Familiarise students with the positions of nearby stars relative to the sun.
• Demonstrate that star patterns, such as the constellations familiar to star gazers on earth, are arbitrary and based on the observer's position.

• Click and drag inside the display window to move the viewing position around the group of nearby stars from a point in deep space.
• Attempt to determine the closest star to the sun by rotating your viewpoint about the three coordinate axes given by the red, green, and blue arrows centred at the sun.
• Given the star patterns visible from a virtual viewpoint in deep space, invent some new constellations that include the sun.
• Change the field of view and note what happens or doesn't happen.

• It is impossible to determine which star is closest to the sun by observing the solar neighbourhood from a single viewpoint only.
• Star patterns are only valid along the current line of sight. These patterns appear to change as you move around deep space.
• Changing the field of view has no effect in parallel projection mode. This mode is provided so that perspective foreshortening does not change the rendered position of stars as a function distance from the viewer.