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Astronomy Year / Week 11 / Friday
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Week 11 · Dark Skies

Friday

How dark is your sky?
// The Milky Way and light pollution
⏱ about 15 min

Friday: How dark is your sky?

Rocket wants to know how many stars hide in light pollution.

Raven makes a plan. "What do you notice before and after the lights go off?"

Nova nods. "Hint: count stars two times and compare."

A dark sky test

  1. Pick one patch of sky, like inside a big square of stars.
  2. Count the stars you see there with the porch light on.
  3. Turn off the outdoor lights you can.
  4. Wait about 30 minutes for your eyes to adjust.
  5. Count the same patch again.
TEST CHECK
  • Read the question.
  • Tap your answer.
After the lights go off, do you expect more or fewer stars?
About how long should your eyes adjust?
RUN THE TEST
  • Tap a card.
  • Then tap its spot.
1First
2Next
3Then
4Last
For a grown-up
Only turn off lights you control.
Keep a red light for walking safely.
Use the same patch of sky both times. That keeps it fair.

Make it a fair test

Count the same patch of sky both times.

Check if the Moon is up.

Write each count down right away.

Then compare the two numbers.

FAIR TEST CHECK
  • Read the question.
  • Tap your answer.
Why count the same patch both times?
You counted 6 stars, then 15. How many more?
What light should you use while you wait?
Which lights can you turn off?
Test factTrue or false?
A bright moon can hide faint stars.?
White light helps your night vision.?
Wait about 30 minutes for your eyes to adjust.?
Count a new patch the second time.?
WHY THIS EXERCISEA fair test lets you trust your results.
Try it
Get your log ready with a grown-up.
Write Lights on and Lights off on a paper.
Draw a box next to each one.
Tomorrow night, write your counts in the boxes.
Draw your patch of sky with lights on and lights off.

Your test is ready! Tomorrow night you run it.

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