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Why is the Sky Purple?

Source Institutions

    Colorado State University

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Why is the Sky Purple?

This simple hands-on activity demonstrates why the sky appears blue on a sunny day and red during sunrise and sunset. Learners observe as a special "sunset egg" and a white light reveal how scattered light emits a blue color and transmitted light emits reddish light. Learners can experiment with different areas of the egg and different light sources to detect interesting variations in color.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
5 to 10 minutes

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 8 - 14

Resource Types:
Activity, Demonstration, Lesson/Lesson Plan


Materials List (per student)


  • Earth and Space Science
    • Earth Structure
      • Atmosphere
      • Earth, Moon and Sun
  • Life Sciences
    • Human Senses and Perception
      • Vision
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
      • Heat Transfer
    • Light and Optics
      • Electromagnetic Spectrum
      • Sunlight and Color
      • Vibration and Waves
    • Vibration and Waves
      • Wave Properties
      • Light and Optics
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Nature and Environment


To use this activity, learners need to:

  • see
  • see color

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



  • All Rights Reserved, Little Shop of Physics, ©2009


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