Exoplanet Detection

Learn about the possible existence of extraterrestrial life, specifically on exoplanets. Learn more about exoplanets and how they are detected in the second video. Then, make your own exoplanet orbit model.

Image Courtesy NASA

Explore the possibility of life on other planets. See what scientists are doing to search for life on other planets.

Courtesy ESA (European Space Agency)

Exoplanet Detection Model

In this activity, you will model the wobble of a star.  Planets orbit around a star, but the orbit of planets around a star result in the "wobble" of that star. 


Planets that orbit a star, outside of our solar system, are called exoplanets.  If a star has planets, the star orbits around a "barycenter" that is not at the very center of that star.  As a result, the star appears to be wobbling.  Scientists can detect a star's wobble using a spectroscope. The amount of "wobble" of a star is related to the size of the exoplanet.  Read more about this phenomenon here.



  • Thin strip of  cardboard

  • Toothpick

  • Paper plate (standard size)

  • Tape

  • Scissor

  • Ruler

  • Wooden pencil

  • Ballpoint Pen

  • Aluminum foil

  • Printable Cutout Sheet for this Activity (Found at the Bottom of the Week 3 Site Page)

Step 1

Cut out the circle from the cutout sheet and glue it to the bottom of the plate.

Step 2

Use a pen to poke a hole in the middle of the plate. Make the hole large enough for a pencil to stick through the plate.

Step 3

Cut a strip of cardboard by 4.25 x 1.25 inches. (These measurements should be about the same as the rectangular cutout from the cutout sheet.)  Glue the paper rectangle on top of the strip of cardboard.  Use a pen to make a hole through the center circle of the cardboard strip. 

Step 4

Stick a toothpick through the diamond on the cardboard strip. Crumple and shape aluminum foil to make a large aluminum foil ball with about a 1.5 inch diameter. Attach the foil ball to the cardboard strip by poking the other end of the toothpick partially through the foil ball.  Insert the toothpick with the foil ball through the diamond on the cardboard strip. Use tape to secure the toothpick and foil ball on top of the rectangular strip.

Step 5

With a scissor, cut off nearly all of the end of the toothpick that extends below the rectangular strip. Use tape to secure the other end of the toothpick to the underside of the cardboard strip.

Step 6

Insert the pencil through the remaining hole (where the center circle was) on the rectangular strip. Pull the pencil down the hole so that nearly all of the pencil is below the plate.  Tape the pencil to the bottom of the cardboard strip. 

Step 7

Place the cardboard strip directly on top of the paper plate, lining up the two holes on top of each other. Stick the wooden pencil (which is attached to the rectangular strip) through the hole in the plate.

Step 8

If more than a quarter inch of the pencil extends above the plate, slide the pencil down the hole in the plate so that no more than the eraser is above the plate.  Tape the top of the eraser to the rectangular cardboard strip.  


Crumple and shape aluminum foil to make a second and much smaller aluminum ball .  Attach this small foil ball to one end of a toothpick so that this ball is at the tip of one end of the toothpick.  With the other exposed end of the toothpick, stick that side of the toothpick through the rectangular cardboard strip as pictured below.  (The toothpick should be placed on the side of the rectangular strip which is on the opposite end of the larger foil ball.) Secure the toothpick in place with tape.

The toothpick should be positioned so that the small foil ball is above the outer ring of the circular cutout. 

Step 9

Rotate the pencil with your fingers to see a model of how a star and exoplanet orbit around their shared center of mass (or barycenter)!

Images of Pillars of Creation, Future Mars Base, Curiosity Rover, Milky Way, Moon, and International Space Station are courtesy of NASA. Image of Earth's atmosphere courtesy of Science Museum of Exploration.