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

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

   • Take out the Sun, since it is not a star
   • 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
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?

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

   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 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
   • The faint one is a planet, since stars are bright
7. 6.

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

   • Elliptical: round, with older stars
   • Spiral: round, with older stars
   • Elliptical: it has spiral arms
   • Irregular: it has no flat disk and no arms
8. 7.

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

   • Galaxies have no stars in them
   • The stars bounce off each other like balls
   • Stars are too small to have gravity
   • The stars are very far apart
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
   • Agree: the galaxies have stayed in the same fixed spots since the start
   • Agree: the universe stays the same size
   • 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?

    • Not right: a light-year is a distance, about 9.5 trillion km
    • Not right: it is the speed of a spaceship
    • Right: it is a time, like a calendar year
    • Right: it is the age of a star
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: stars have no temperature
    • Agree: red is the hottest color for stars
    • Disagree: blue stars are hotter; red stars are cooler