Stars, galaxies and the universe

Grade 6 Science Worksheet

Circle the best answer.

1. Read this first

   Galaxy seen from above, not to scale

   a flat disk with a central bulge and spiral arms, more than 100,000 light-years across. Dot S sits on one spiral arm, about halfway from the center to the edge.

2. 1.

   In the galaxy drawing, dot S marks the Sun. Where in the Milky Way is the Sun, Ari?

   • At the outer edge, past the arms
   • At the very center of the galaxy
   • Outside the galaxy, looking in
   • On a spiral arm, about halfway out
3. 2.

   Bo reads that, from a dark place, the Milky Way looks like a faint milky band across the sky. Why a band?

   • It is a thin cloud in Earth's air
   • It is the light of one huge star
   • It is the light of the solar system's planets
   • We see the galaxy's flat disk edge-on from inside
4. 3.

   Esme lists four things from smallest to largest for a poster. Which order is right?

   • Earth, Milky Way, solar system, Local Group
   • Earth, solar system, Milky Way, Local Group
   • Earth, solar system, Local Group, Milky Way
   • Solar system, Earth, Milky Way, Local Group
5. 4.

   Proxima Centauri is 4.24 light-years away. What does a light-year measure, Jun?

   • A distance: how far light goes in a year
   • A brightness: how much light a star gives off
   • A time: how long a spaceship takes to get there
   • A time: the length of a year on Proxima
6. 5.

   A star is 10 light-years from Earth. Which statement about it does Kira find true?

   • It is 10 km away
   • It is 10 years old
   • Its light takes about 10 years to reach us
   • A spaceship would reach it in about 10 years
7. 6.

   The Andromeda Galaxy is about 2.5 million light-years away (NASA). When did the light that reaches Luz tonight leave it?

   • About 2.5 million years ago
   • About 2.5 million seconds ago
   • About 2.5 billion years ago
   • Just last night
8. 7.

   Proxima Centauri is a red dwarf, the smallest kind of main sequence star (NASA). What else is true of red dwarfs, Noah?

   • They are the hottest main sequence stars
   • They are the coolest main sequence stars
   • They are planets, not stars
   • They are hotter than blue stars
9. 8.

   About 90% of stars, the Sun included, are main sequence stars (NASA). What is happening in their cores, Pia?

   • Hydrogen is fusing into helium
   • Nothing, as their cores are cold
   • Coal is burning
   • Helium is splitting into hydrogen
10. 9.

    In 1929, astronomers found that the universe is expanding. What does that tell Tala about the far past?

    • It began expanding in 1929
    • It was once smaller and much hotter
    • It has stayed the same size
    • Galaxies are shrinking
11. 10.

    The cosmic microwave background is the oldest light we can observe (NASA). About when was it given off, Zee?

    • About 4.6 billion years ago, given off by Earth
    • About 380,000 years after the big bang
    • Last year, by the Sun
    • Before the universe began