Circumpolar Motion

Circumpolar Motion

Button controls

Help button
Help button: This button will open a window with help information.
Toggle controls
Show/Hide constellations: This button will add constellation lines to the stars depicted.
Command buttons
Reset button
Reset: reload the applet and reset the parameters.
Rewind button
Rewind: press and hold to advance the applet in reverse.
Pause button
Pause: temporarily stop the action in the applet.
Play button
Play: begin or resume the action in the applet.
Fast forward button
Fast Forward: press and hold to advance the applet.
End button
End: advance the applet to its end.
Speed button
Speed: click to select the number and input a higher number to increase the speed of the rewind and fast forward buttons.
Slider bar
Slider bar: shows the progression through the animation.
Drag controller
Drag controller: click and drag over this symbol to reposition the controller buttons within the applet frame.
Toggle controls
Collapse button: click this button to collapse controller button.

Using the applet

This applet has been designed to help students visualize the concept of the circumpolar motion of the stars. It consists of four key components: the star field; the pole star; the hour indicators; and the constellations.

Circumpolar motion is the apparent rotation of all the stars in the northern hemisphere around the pole star, Polaris. The positions of the stars remain constant with respect to each other; therefore, the constellations maintain their shapes. The stars make one complete rotation every 24 hours (one day).

Within the applet, the horizon is used to illustrate the fact that not all stars are circumpolar. The height of the North Star in relation to the horizon depends on the latitude at which the observer on Earth is situated.

Download the Flash Applet