In this section of the lab your instructor will show you a model of a spinning asteroid. A very bright light is made to shine on the model, and the reflected light is measured by a small photosensor. The changing light level is shown on a graph. Discuss the following questions with your team:

• Can the period of the model asteroid's rotation be determined from its lightcurve? In what way?
   
• How does the shape of the light curve depend on the shape of the asteroid? What sort of lightcurve would you expect for a spherical asteroid, or for an egg-shaped asteroid?

Images of several large asteroids have been provided for this exercise. The photometry tool found in the MaxIm software works by measuring the pixel intensity of objects in an image and can be set up to plot the changing intensity of a moving object. The Photometry in Maxim tutorial should help you do this.

You can make a rough determination of the asteroid's rotation period from this light curve, but if you want a more accurate result you can use a data analysis program such as Logger Pro.

Finding the Period in Logger Pro

• Once you’ve produced a light curve in Maxim, export the data as a comma separated value or .csv file
   
• Open up Logger Pro and import your light curve data from the .csv file.
   
• Use the curve fit tools in Logger Pro to determine the period of the asteroid.