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 galaxy is far bigger than the gaps between nearby stars
   • The Milky Way is about as big as the solar system
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 stays the same as long ago
   • It grows inside our solar system instead
   • It shrinks as the universe cools
   • It keeps growing
4. 3.

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

   • Sirius is a planet
   • The Sun is a planet, so it glows more
   • Sirius gives off no light of its own
   • The Sun is far closer to Earth
5. 4.

   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 hotter, since faint stars are red
   • The faint one is a planet, since stars are bright
   • The faint one is closer, since faint means near
   • The faint one is farther away, so less of its light reaches us
6. 5.

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

   • Spiral: round, with older stars
   • Irregular: it has no flat disk and no arms
   • Elliptical: round, with older stars
   • Elliptical: it has spiral arms
7. 6.

   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
   • Two stars in our solar system
   • Satellite galaxies of the Milky Way
   • Parts of the solar system's outer edge
8. 7.

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

   • The stars bounce off each other like balls
   • The stars are very far apart
   • Stars are too small to have gravity
   • Galaxies have no stars in them
9. 8.

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

   • Agree: the universe stays the same size
   • Agree: the galaxies have stayed in the same fixed spots since the start
   • Disagree: it began 4.6 billion years ago
   • Disagree: it began hot and dense and has been expanding
10. 9.

    A video says a light-year is how long a year lasts on a far planet. What should Tala write beside it in a class notebook?

    • Right: it is a time, like a calendar year
    • Not right: it is the speed of a spaceship
    • Right: it is the age of a star
    • Not right: a light-year is a distance, about 9.5 trillion km
11. 10.

    Zee's cousin says red stars are the hottest, since red means hot on a stove. Which response fits?

    • Agree: reddish Betelgeuse must be hotter than our yellow Sun
    • Disagree: blue stars are hotter; red stars are cooler
    • Agree: red is the hottest color for stars
    • Disagree: stars have no temperature