Spinning Patterns

You can create unexpected patterns by drawing in the sand on these spinning disks. You may draw a straight line, for instance, but what appears on the disk is a spiral. The patterns you make result from adding the motion of your hand to the spinning motion of the disk.

Like a speck of sand on the “Spinning Patterns” turntable, a person on the surface of the earth is on a rotating surface. If you are in the southern hemisphere looking north toward the equator, Earth appears to be rotating clockwise. On the northern hemisphere, it appears to rotate counterclockwise.

A satellite orbiting Earth also has an unexpectedly wavy flight pattern even though it appears straight. You can test this for yourself with a globe and a marker. Imagine that your satellite is orbiting in a clockwise direction. Take a washable marker and mark an “X” on a line of longitude. Move clockwise and mark a spot on the next longitude line. Draw a line to connect this X with the next one. This is the orbital path. Continue this 10 more times, connecting the X’s. When this is completed, you will have made two complete revolutions around Earth. Transfer the data from the globe onto a flat Goode’s map (also known as an “orange peel” map) by locating the correct points of longitude and latitude. Connect the X’s to plot the flight path. Note that the orbiter’s flight path appears as a wavy line.

NASA often tracks the path of man-made satellites from a viewpoint high above the orbiter, looking down at Earth. Because Earth is spinning on a tilted axis, objects orbiting Earth seem to have a wavy flight path. After completing these activities, you should understand that the combined movements of Earth and the orbiter result in what appears to be a wavy flight path.

Questions to Ask

Why do objects (such as storms and planes) follow a curved path as they travel near the surface of the Earth? What is this deflection called?

What are the bands of wind currents called that were used by early sailors/traders to travel between Europe and the Americas? Why were their winds so reliable and predictable?

What motion would you have to use to draw a straight line on the rotating disc?

Relevant Arkansas Science Frameworks

ESS.8.7.1, ESS.8.7.2, ESS.8.7.3, ESS.8.7.4, ESS.8.8.1, ESS.8.8.2, ESS.8.7.8

"Mini-Vibe" — An activity to do at home or in the classroom