Light on Other Planets

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In this math-based activity, learners model the intensity of light at various distances from a light source, and understand how astronomers measure the amount of sunlight that hits our planet and others. Learners solve an equation for light intensity, and come to grasp how the amount of light reaching a planet strongly determines its habitability. This activity can be found on pages 31-32 of the activity guide. [Activity is publicly available through a web crawler capture on]

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
45 to 60 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 11 - adult

Resource Types:
Activity, Lesson/Lesson Plan, Simulation


Materials List (per group of students)

  • Worksheet - Our Solar System to Scale
  • Overhead projector or flashlight
  • Blackboard, eraser board or chart paper
  • Colored marker or chalk
  • Worksheet – Light on Other Planets
  • Ruler (centimeters)


  • Earth and Space Science
    • Astronomy
    • Earth, Moon and Sun
    • Solar System
      • The Sun
      • The Planets
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
    • Light and Optics
      • Reflection and Refraction
      • Sunlight and Color
  • Mathematics
    • Algebra
      • Equations and Inequalities
    • Geometry
      • Plane Geometry
    • Measurement
      • Units of Measurement
      • Circles


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Access Rights:

  • Free access


Source Collection

  • Science After School Consumer's Guide


  • All rights reserved, TERC, 2007

Funding Sources:

  • NASA, NAS5-26555
  • National Science Foundation, NSF 9730728