Redshift and the Expanding Universe

Lab Brief #4

🎯 Your mission

Set it up. Test it. Be amazed.

⚡ The twist

Up there, the rules of down here stop working.

What you'll learn

Light from distant galaxies is stretched to longer wavelengths, and the further away a galaxy is, the greater the shift. That relationship implies space itself is expanding, which is the strongest evidence for the Big Bang some 13.8 billion years ago.

Key words

redshift
The lengthening of light's wavelength from a receding source.
Big Bang
The model in which the universe began expanding from an extremely hot, dense state.

Make a hypothesis first

Predict: what would happen on the moon vs. on Earth?

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

Get ready

🧰 What you need

balloon
marker pen
flexible tape measure

⚠️ Safety first

Do not over-inflate; burst fragments are a choking hazard.

Step 1 of 4 · Read

Think about what you just learned: say what "redshift" and "Big Bang" mean in your own words before you start.

Step 2 of 4 · Do

Draw dots on a deflated balloon, measure the separations, inflate it and measure again. Show that every dot sees every other receding, and that the most distant dots recede fastest — a two-dimensional model of expanding space.

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 2

Light from a receding galaxy is shifted towards:

How sure are you?😐 maybe

Question 2 of 2

The redshift-distance relationship supports the idea that:

How sure are you?😐 maybe

Mind = blown

🪐 A day on Venus is longer than a year on Venus.

Nice work!

You got 0 of 2 right.

Next: Cosmic Microwave Background Radiation All lessons

🎯

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✨ 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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