8B30.95 - Forward, Backward, and Side Scattering - Zodiacal Light

Code Number:
Demo Title:
Forward, Backward, and Side Scattering - Zodiacal Light
Area of Study:
Stellar Astronomy
Laser and Tank with Fluorescein dye, small water tank, coffee creamer, green laser pointer with mounting apparatus, Lazy Susan.

Aim the laser into one of the ends of the large fish tank containing the fluorescein dye or a small amount of Pine-Sol.  Then, you can either turn the table or walk around the table, while observing the different amounts of scattering.  There will be a pronounced amount of forward scattering in this demonstration. 

Attach the laser assembly to the small tank, fill it to approximately 2/3 full and place this onto the Lazy Suzan.  Add powdered coffee creamer to the water until the laser beam looks to be completely scattered about 1/2 way through its travel through the tank.  The laser beam is quite visible when viewed behind the laser or in the backscattered orientation, seems to travel about 1/2 way through the tank before being completely scattered when observed from the side, and seems to be completely scattered with no clear laser beam source when viewed from the forward scattered orientation.

  • Jearl Walker, "6.149, Zodiacal Light, Gegenschein and Other Nocturnal Lights", The Flying Circus of Physics Ed. 2, p. 302.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.