Lesson 1: Our Home in the Milky Way


This lesson will require approximately one 30-minute period.


Demonstrate the importance of using the languages of science and technology to compare and communicate ideas, processes, and results (e.g., use appropriate terminology such as "constellations," "planets," "moons," "comets," "asteroids," and "meteors" to describe objects in space)
Identify various methods for finding answers to given questions and solutions to given problems, and select one that is appropriate (e.g., use local papers or science periodicals for listings of planets that are visible at a particular time)
Draw a conclusion, based on evidence gathered through research and observation, that answers an initial question (e.g., conclude that simulated flour craters are deeper and wider when the marble is heavier or is dropped from greater heights)

General Objectives

The students will gain an appreciation for the vast scale of the Milky Way Galaxy.

Lesson Overview

This lesson has been designed to help students gain an appreciation for the vast scale of the Milky Way Galaxy by viewing an applet showing Earth's place in our galaxy.

Materials and Resources

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  • galaxy
  • Milky Way
  • light year
  • Astronomical Unit

Developing the Lesson

Have students hypothesize as to how long it would take to journey from Earth to Pluto at a cruising speed of 100 km/hr (approximately 6581 years); now, how long would it take to cross our galaxy (about 1.7 trillion years)? As students will see, our galaxy is enormous, and is only a very small part of the universe as a whole.

Introduce the applet, Our Home in the Galaxy, to illustrate this point. Show our solar system's position on one of the spiral arms of the Milky Way, and make note of the changing distance given at the top of the applet, remembering that one AU is equal to the distance between the Earth and the Sun.

Present the following questions to students, and give them 10 minutes to discuss them with a partner before reconvening and discussing as a class.

  • What is a galaxy? (A system of millions or billions of stars and interstellar gases and material, held together by gravity.)
  • What is the Milky Way? (Our home galaxy, seen as a luminous band of cloud stretching across the sky.)
  • How old is our galaxy? (about 8 billion years old)
  • Are there other galaxies like the Milky Way? (It is estimated that there are billions of other galaxies like ours.)
  • What is at the centre of the Milky Way? (Many believe it to be a black hole, holding the galaxy together with its gravity)


Review the lesson's vocabulary orally with students.


Assess student understanding through questions and observation.