Solar and Lunar Eclipses

Solar and Lunar Eclipses

Button controls

Help button
Help button: This button will open a window with help information.
Toggle controls
Toggle controls:
  • Total Eclipse - This button will display a graphic depicting the alignments for a total solar eclipse
  • Partial Eclipse - This button will display a graphic depicting the alignments for a partial solar eclipse
  • Annular Eclipse - This button will display a graphic depicting the alignments for an annular solar eclipse

Using the applet

This applet has been designed to help students visualize the concept of solar and lunar eclipses. Students will use the applet to display graphics depicting the alignments of the Sun, Moon and Earth that produce the different kinds of eclipses.

From the initial screen, students will select one of three possible types of solar eclipses. The guiding text comments that eclipses depend on the correct alignment of the Sun, Moon and Earth.

Solar and Lunar Eclipses

After selecting a type of eclipse, the graphics change to indicate how the Sun's rays cast shadows on the Earth. The resulting shadows on Earth produce the eclipse we observe. Students can use the other toggle buttons to observe and compare the alignments producing the different kinds of eclipses. At any point, students can click on the "Tell me more" button to learn more about the alignments of the Sun, Moon and Earth.

Solar and Lunar Eclipses

After clicking on the "Tell me more" button, the graphics change to show both the Moon's orbit around the Earth and the Earth's orbit around the Sun. Students should note that the Moon's orbit around the Earth is tilted with respect to the Earth's orbit around the Sun. At this point, students have the opportunity to view when the Earth, Moon and Sun line up or when they do not.

Solar and Lunar Eclipses

Once students have selected the alignment scenario they wish to observe, the graphics are changed yet again. This time, the graphics depict the three-dimensional orientations of the Sun, Moon and Earth. Students can then use the controller buttons to play the animation. As the animation progresses, the Moon continues its orbit around the Earth and the graphic at the bottom left indicates what observers on Earth would see. The buttons shown at the top left enable students to return to previous sections of the applet or to view the other alignment scenario. For more information about the controller buttons, see below.

Controller buttons

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.

Download the Flash Applet