Detecting Planets Around Other Stars

Lab Brief #10

🎯 Your mission

Predict it first. Then prove yourself right (or wrong).

⚡ The twist

The light you see now started its trip a long time ago.

What you'll learn

Most exoplanets are found by the transit method: a planet crossing its star dims it very slightly, on a repeating schedule. The depth of the dip gives the planet's size and the interval gives its year.

Key words

transit
The passage of a planet across the face of its star, causing a small repeating dip in brightness.
light curve
A graph of a star's brightness against time, in which transits appear as regular dips.

Make a hypothesis first

Guess: how big does that look from here vs. from there?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

lamp
light sensor or phone app
beads of three sizes
string
graph paper

Get ready

⚠️ Safety first

Small beads are a choking hazard — keep them away from young children.

Step 1 of 4 · Read

Think about what you just learned: say what "transit" and "light curve" mean in your own words before you start.

Step 2 of 4 · Do

Model a transit by moving beads of three different sizes across a lamp while a light sensor records brightness. Plot each light curve, measure the depth and spacing of the dips, and rank the beads by size from the depths alone.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 3

In the transit method, the depth of the dip in brightness gives the planet's:

How sure are you?😐 maybe

Question 2 of 3

The time between repeated transits gives the planet's:

How sure are you?😐 maybe

Question 3 of 3

A light curve is a graph of a star's brightness against:

How sure are you?😐 maybe

Mind = blown

🌌 If you could drive a car straight up at highway speed, you'd reach space in under an hour.

Nice work!

You got 0 of 3 right.

All lessons

🎯

Next Smart Experiment

We'll pick an experiment that matches exactly how you're thinking right now.

✨ More to explore

🌍 Where you see this in real life: GPS, weather forecasts, and the seasons all rely on this.

🏆 Stretch challenge (try it this week): Find a constellation in the sky. Look it up. Tell someone its story.

👨‍👩‍👧 For the dinner table: “If you could visit any planet, which would you pick and why?”

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Detecting Planets Around Other Stars

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