Stars, galaxies and the universe

Grade 6 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use this

   Nested boxes, not to scale, each box drawn inside the next. Box W: the Sun and its planets. Box X: Box W plus more than 100 billion other stars. Box Y: Box X plus over 50 other galaxies. Box Z: Box Y plus many more groups and clusters of galaxies.

2. 1.

   Light reaches us from the nearest star in about 4.24 years, but takes more than 100,000 years to cross the Milky Way. What does that show, Ari?

   • Light slows down inside the galaxy
   • A light-year is a length of time
   • The Milky Way is about as big as the solar system
   • The galaxy is far bigger than the gaps between nearby stars
3. 2.

   Box Z, the universe, is about 13.8 billion years old and still expanding (NASA). What is happening to the space between far-apart galaxy clusters, Bo?

   • It keeps growing
   • It stays the same as long ago
   • It grows inside our solar system instead
   • It shrinks as the universe cools
4. 3.

   Esme's classmate draws the Milky Way inside the solar system. Which fix is right?

   • Swap them: the solar system is a tiny part of the Milky Way
   • Draw the two the same size
   • Keep it: the solar system is big enough to hold the whole galaxy
   • Take out the Sun, since it is not a star
5. 4.

   Two stars give off the same amount of light. Star P is 10 light-years away; star Q is 100 light-years away. Which looks brighter from Earth, Jun?

   • They look equally bright
   • Star Q, the farther one
   • Star P, the closer one
   • Star Q, since 100 light-years is a longer time
6. 5.

   Sirius is the brightest star in the night sky (NASA), yet the Sun outshines it by far. Which explanation fits, Kira?

   • The Sun is far closer to Earth
   • Sirius is a planet
   • Sirius gives off no light of its own
   • The Sun is a planet, so it glows more
7. 6.

   Luz reads about a faint star and a bright star that give off the same amount of light. Which claim, with its reason, fits?

   • The faint one is a planet, since stars are bright
   • The faint one is closer, since faint means near
   • The faint one is hotter, since faint stars are red
   • The faint one is farther away, so less of its light reaches us
8. 7.

   Galaxy card: round, no flat disk, made mostly of older stars. Milo must name the shape and one clue. Which answer fits?

   • Elliptical: it has spiral arms
   • Irregular: it has no flat disk and no arms
   • Spiral: round, with older stars
   • Elliptical: round, with older stars
9. 8.

   The Large and Small Magellanic Clouds are small galaxies about 160,000 light-years away that orbit the Milky Way. What are they, Noah?

   • Clouds of water in Earth's sky
   • Parts of the solar system's outer edge
   • Two stars in our solar system
   • Satellite galaxies of the Milky Way
10. 9.

    When two galaxies collide, the stars inside them do not crash into each other (NASA). Why not, Pia?

    • The stars are very far apart
    • The stars bounce off each other like balls
    • Stars are too small to have gravity
    • Galaxies have no stars in them
11. 10.

    Ren's friend says the universe has always looked the same as it does now. Which response is best?

    • Disagree: it began 4.6 billion years ago
    • Agree: the galaxies have stayed in the same fixed spots since the start
    • Disagree: it began hot and dense and has been expanding
    • Agree: the universe stays the same size