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The Geophysical Light/Dark Cycle

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The Geophysical Light/Dark Cycle

This is an activity (located on page 131 of the PDF) related to sleep and circadian rhythms as well as space travel. Learners will discover how the light/dark cycle is dictated by the rotation of Earth. In addition, learners will examine the annual changes in the duration of light each day as the planet orbits the sun. Learners will also discuss the implications in the light/dark cycle for astronauts aboard an orbiting spacecraft. This activity can be enhanced by sharing the "Astronaut's Sleep" Podcast with learners (see related resource link). This resource guide includes background information and sample evaluation questions.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
45 to 60 minutes

Estimated Materials Cost:

Age Range:
Ages 8 - 18

Resource Types:
Activity, Demonstration, Lesson/Lesson Plan, Simulation


Materials List (per group of students)

  • Globe
  • Flashlight
  • Pencil


  • Earth and Space Science
    • Astronomy
      • Probes, Satellites and Spacecraft
    • Earth Structure
      • Earth, Moon and Sun
    • Earth, Moon and Sun
      • Days
    • Solar System
      • The Sun
  • Life Sciences
    • Human Body
      • The Brain and Nervous System
  • Mathematics
    • Algebra
      • Patterns
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
      • Data Representation
    • Measurement
      • Circles
  • Physical Sciences
    • Motion and Forces
      • Gravity
      • Rotation Motion
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Formulating Explanations


To use this activity, learners need to:

  • see
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Includes alignment to state and/or national standards

This resource is part of:

Access Rights:

  • Free access


  • MacLeish, Marlene Y.; McLean, Bernice R.


  • Public Domain, NASA,


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