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

Wednesday

Light that hides the stars
// The Milky Way and light pollution
⏱ about 15 min

Wednesday: Light that hides the stars

Rocket looks up in the city. "Where did all the stars go?"

Raven looks around. "What do you notice? Bright lights everywhere."

Nova points at a lamp shining up. "Hint: some light goes where it is not needed."

Light pollution

Light pollution is extra light that spills into the night sky.

It comes from streetlights, parking lots and other outdoor lights.

It makes the sky glow and hides faint stars.

Most people in the world cannot see the Milky Way from home.

That is about 8 out of every 10 people!

LIGHT CHECK
  • Read the question.
  • Tap your answer.
What is light pollution?
Out of 10 people, about how many cannot see the Milky Way?
BRIGHTEST SKY TO DARKEST SKY
  • Tap a card.
  • Then tap its spot.
1Brightest
2Middle
3Darkest
Moonlight counts too
A bright moon also lights up the sky.
Faint stars are easier to see on moonless nights.

Where stray light comes from

Some outdoor lights shine up or sideways.

That light does not help anyone see the ground.

It spills into the sky instead.

The sky glows, and faint stars fade away.

STRAY LIGHT DETECTIVE
  • Read the question.
  • Tap your answer.
Where does light pollution come from?
What does a glowing sky hide?
Where can you see more stars?
What else can light up the night sky?
Light pollution factTrue or false?
Streetlights can add to light pollution.?
Light pollution makes more stars appear.?
Parking lot lights can light up the sky.?
Most people can see the Milky Way from home.?
WHY THIS EXERCISEKnowing where stray light comes from helps us fix it.
HOW STRAY LIGHT HIDES STARS
  • Tap a card.
  • Then tap its spot.
1First
2Next
3Last
Try it
Look out a window at night with a grown-up.
Count the outdoor lights you can see.
Which ones shine up or sideways?
Which ones point down?
Safety first
Stay inside by the window.
A grown-up stays with you.
Draw two skies: one over a city, one over a dark park.
Many stars above a glowing curved band of air. Below, Earth is dark with clusters of orange city lights.

City lights seen from space. Astronauts took this from the International Space Station.

It shows lights where Europe meets Asia, on March 20, 2020.

The stars are above. The city lights shine below.

Image credit: NASA (photo iss062e103874)

You know what hides the stars! Tomorrow we learn how to help.

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