Parallax

Astronomy, Math:	Parallax, Triangulation
Grade Range:	Middle School, High School
Format:	Hands-on, Stage

In order for students to benefit much from this demonstration, they will need some basic trigonometry skills prior to the presentation. This demonstration is very informative and a great basis for lessons in Astronomy, but students might struggle with the calculations.

Materials

• Large Rectangular White Board
• White Board Markers
• Laser Pointers
• Test Tube Stand with Holder
• Small Plastic Star
• Masking Tape or Painters Tape
• Paper and Pencil

Safety Precautions

Please read the General Safety Precautions section of the Demonstration Safety page before performing this demonstration.

Demonstration

1. Set up the white board, either propped up or against a wall, and use the tape to mark a spot 10 feet in front of the board. Put the stand on the marked spot, and then mark another spot 10 feet further along the same line and mark it. This will be where the volunteers stand.
2. Have two volunteers come up. Have one stand on the left side of the marked spot and use the laser pointer to point at the star. Mark the spot where the laser lands on the white board, and then have the second volunteer do the same, but stand on the right side of the marked spot. Mark their spot on the white board.
3. For a hands-on event, give everyone at the table a pencil and paper and ask them to draw the scenario as you draw it, and provide the explanation. Otherwise, for a stage show, go straight into the explanation.

Additional Information

• Any extra tidbits that do not fit into other sections
• This demonstration is a part of the (insert Stage Show here)

Real Life Examples

We use parallax every day in the depth perception of our vision. The Global Positioning System (GPS) uses a technique related to parallax called triangulation to figure out where you are on the Earth's surface based on the GPS receiver's "observations" of signals from satellites in orbit.