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Our Galaxy
Why does everything in space seem to spin and swirl together?

Imagine zooming out from Earth and seeing it as just one planet orbiting one star in one galaxy made of billions of stars. In this lesson, your learner discovers our cosmic address: we live on a small planet in a tiny solar system inside a swirling island of stars called the Milky Way. Understanding this gives kids a sense of both their place in the universe and the incredible scale of it all.

S2S_Lesson03_GALAXIES_THE_SOLAR_SYSTEM.pptx by Selene


Key Ideas

  • We live in a galaxy called the Milky Way, which is made of stars, planets, gas, and dust.
  • The Milky Way is a spiral galaxy, and our solar system orbits within one of its arms.
  • Our solar system formed from a cloud of gas and dust, which were pulled together by gravity and eventually became the Sun and planets.
  • Our solar system has the Sun at its center, and 8 planets orbit around it in their own paths.
  • The Sun is a star, and the planets (including Earth) are much smaller objects that travel around it.

Spine Reading
  • DK's Science as You've Never Seen it Before:
    • Galaxies pg. 114-115
    • The Solar System pg. 120-121
  • Mammoth Science: Solar System pg. 152, Milky Way pg. 154
  • Visual Timelines: Life on Earth pg. 10
  • Alternative: NASA’s Space Place (explore the website)
     
✏️  Notebooking Activity
Label each planet in the solar system diagram and write one word that describes something special about it (e.g., "hottest," "biggest," "has rings," "icy").

Vocabulary
  • Galaxy — A huge collection of stars, gas, dust, and dark matter held together by gravity; our galaxy is the Milky Way.
  • Solar System — Our sun and everything that orbits it — eight planets, moons, asteroids, comets, and other objects.
  • Orbit — The curved path one object takes around another due to gravity, like Earth's path around the Sun.
  • Planet — A large, round object that orbits a star and has cleared the space around its orbit.
  • Asteroid — A rocky object, smaller than a planet, that orbits the Sun; many are found in the Asteroid Belt between Mars and Jupiter.

Discussion Questions
  • What is the name of the galaxy we live in? 
    (Sample answer: We live in the Milky Way.)
  • What kinds of things are found in the Milky Way? 
    (Sample answer: The Milky Way has stars, planets, gas, and dust.)
  • How is the Milky Way shaped, and what is it made of? 
    (Sample answer: The Milky Way is a spiral galaxy made of stars, planets, gas, and dust.)
  • Where is our solar system located within the Milky Way? 
    (Sample answer: Our solar system is in one of the spiral arms of the Milky Way.)
  • What star is part of our solar system? 
    (Sample answer: The Sun is the star in our solar system.)
  • How is a galaxy different from a solar system? 
    (Sample answer: A solar system has one star and its planets, but a galaxy has billions of stars and many solar systems.)
Digging Deeper
  • How might our place in the Milky Way affect what we see from Earth? 
    (Sample answer: Because we are inside the galaxy, we see the Milky Way as a band of stars across the sky.)
  • Could there be life outside our Solar System? 
    (Answers will vary)

Timeline PageLabel the next page in your timeline “Our Solar System Forms: 4.6 Billion Years Ago”. The workbook prompts learners to draw a spiral galaxy from above with a small arrow pointing to a dot near one of the outer arms labeled “You Are Here,” and beside it a tiny solar system with the Sun at the center and eight planets orbiting around it.

Cosmic CalendarWhere we are: September 9
We jump forward more than eight months on the Cosmic Calendar today. Read the script below before the lesson.

Read aloud: Look at how far we’ve jumped on the Cosmic Calendar. Last lesson we were on January 1st. Today we’re all the way to September 9th. That means more than eight months of cosmic time passed between the first stars forming and our own solar system coming together. In real years, that’s about 9 billion years. Nine billion years of stars being born and dying, galaxies colliding and growing, heavy elements being forged inside exploding stars, all of that had to happen first before there was enough material to build our sun and our planets. September 9th. That’s when our solar system gets its start. We’ve got a long way to go before December 31st, but from this point forward, everything we study is a little closer to home.

SCIENTIST SPOTLIGHT: Vera Rubin

Vera Rubin was an American astronomer who spent decades studying how galaxies rotate. What she found did not match what the laws of physics predicted: the outer edges of galaxies were spinning just as fast as the inner parts, which should be impossible unless there was far more matter present than anyone could see. Her work provided the strongest evidence yet for the existence of dark matter, the invisible substance that makes up most of the universe. Rubin was repeatedly passed over for major awards and recognition during her lifetime, and she was the first woman allowed to use the Palomar Observatory. She died in 2016 without receiving a Nobel Prize that many scientists believe she deserved.

Videos:Books:
Digging Deeper Activity:
What is dark matter, and why can we not see it? Research the evidence scientists use to prove something exists even when it cannot be directly observed. How is this similar to or different from how we know the Big Bang happened?

Sources and More Information:

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