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
   • The Milky Way is about as big as the solar system
   • The galaxy is far bigger than the gaps between nearby stars
   • A light-year is a length of time
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 shrinks as the universe cools
   • It keeps growing
   • It grows inside our solar system instead
4. 3.

   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?

   • Star P, the closer one
   • Star Q, since 100 light-years is a longer time
   • Star Q, the farther one
   • They look equally bright
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 farther away, so less of its light reaches us
   • The faint one is closer, since faint means near
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: it has spiral arms
   • Elliptical: round, with older stars
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?

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

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

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

   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
   • Disagree: it began hot and dense and has been expanding
   • Agree: the galaxies have stayed in the same fixed spots since the start
   • Agree: the universe stays the same size
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
    • Right: it is the age of a star
    • Not right: a light-year is a distance, about 9.5 trillion km
    • Not right: it is the speed of a spaceship
11. 10.

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

    • Disagree: stars have no temperature
    • 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