10: Exoplanet Detection - Transit Method
- Page ID
- 163002
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Lab Overview
Lab Goals
The goal of this lab is to develop the scientific practices of collecting and interpreting data:
- Make connections between measured data and planetary orbit positions/velocities
- Identify patterns relating mass (planet and star), orbital distance, orbital speed, and measured light properties for transit measurements
Equipment and Setup
This lab requires the following equipment on each table.
- Computers with internet for simulation
Submission Instructions
Submit a brief lab report that includes the following sections:
Results
- Light Curve Drawings
- Data
Discussion
Write your answers to the Discussion Questions using the Claim-Evidence-Reasoning format.
Background Information
Light Intensity

We can see and measure the light from other stars in our galaxy. Planets are smaller and darker, so we cannot see them directly. However, we can detect them when they pass in front of a star and cast a small shadow that reduces the total amount of light our telescopes receive. The transit method detects planets and uses the characteristics of the light curve to infer properties about the planet and its orbit. A Normalized Flux of 1.000 is the full start light. The other values on the graph can identify the percent of starlight that reaches us (0.990 = 99% of the light or 1% of light is blocked).
Lab Instructions
Simulation Setup
Open the Transit simulation from the University of Nebraska Astronomy Education website:
Part 1 - Transit Measurements
Procedure
- Animate the orbit by moving the phase slider from one end to the other.
Make sense of the model
- Where is the planet when the normalized flux is 1.000?
- Where is the planet when the normalized flux is below 1.000 and a flat line?
- Where is the planet when the graph slants down or up?
Part 2 - Planet Properties
Procedure
- Set inclination to 90o
- Choose one slider in the Planet Properties controls at a time and make changes. Examine effects on the orbit, the light curve, and the period of the eclipse
- Repeat for the other slides
Discussion Questions
- Make a claim about the effect of each planet property on each of the following:
- Light Curve depth
- Light Curve eclipse time
- Total Orbital Period
Part 3 - Star Properties
Procedure
- There is only one star property (mass). Change it without changing anything else and examine effects on the orbit, the light curve, and the period of the eclipse
Discussion Questions
- Make a claim about how the mass of the star does/does not affect:
- Light Curve depth
- Light Curve eclipse time
- Total Orbital Period


