Illustration of a distant exoplanet

Finding Exoplanets

Transit Method Activity

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In this activity, you will have the opportunity to discover exoplanets using the common transit method. You will look over the following graphs and determine if there is an exoplanet orbiting the star or not.

Using the Transit Method

1. First determine what is the light curve. Remember light curves are not perfect straight lines, so be prepared to for the light curves to be wavy, curve up, or curve down.

2. After you have determined your star’s baseline. Look for dips. You need to find dips that are going down from the light curve. These indicate that there is something that is going in front of the star and blocking its light.

3. Make sure you look for at least three dips! If there are less than three dips there is a good choice that it is not a planet blocking the star’s light. More than three dips indicate that there is a good chance that a planet is orbiting the planet.

Comples graph illustrating dips in light curves

There is more than three dips. Also each dip happens consistently, every 80 days. There is a good chance this an orbiting exoplanet.


Try It Out Yourself

1. Look at the following graphs.

2. Based on the information above try to figure out which graphs have exoplanets and which do not.

3. After making your guesses check your answers on the last page. Try not to cheat!

Helpful Website:

line graph with slowly increasing trend line

Line graph with early peak then slow decline of trend line

Line graph with mostly flat trend line, then slight increase at the end

line graph with distinct break in the trend line

line graph with straight increasing progression

Line graph with jagged upward trend line


Answer key from graphs (in order in which they appear)

A. No Exoplanet

B. Exoplanet

C. Exoplanet

D. No Exoplanet

E. Exoplanet

F. Exoplanet