The evidence for the Big Bang

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Table, Evidence for the Big Bang (NASA, ESA), with columns Observation, What it shows

   Galaxy redshifts grow with distance, space is expanding; microwave background at about 2.7 K, a hot, dense early universe; mostly hydrogen and helium, a little lithium, early element-making.

2. 1.

   Match each observation to what it supports. Which pairing is right, by Bo's reading?

   • Redshifts: hot start; background: expansion
   • Elements: expansion; redshifts: element-making
   • Background: starlight; redshifts: galaxy color
   • Redshifts: expansion; background: hot start; elements: early element-making
3. 2.

   Timeline with galaxies drawn closer together further back in time. If galaxies are moving apart today, what was the universe like long ago, by Esme's reading?

   • Packed into one spot in empty space
   • Exactly the same as today
   • Closer together, hotter and denser
   • Farther apart and colder

4. Background temperature (NASA, ESA)

   Time	Temperature
   at release	about 3,000 K
   today	about 2.7 K

5. 3.

   The background light was about 3,000 K when released and is about 2.7 K now. By about what factor has space stretched, by Jun's math?

   • About 0.0009
   • About 11
   • About 3,003
   • About 1,100
6. 4.

   All-sky map of the background with tiny temperature differences. The background is nearly the same temperature in every direction, with only tiny differences (NASA). What does this suggest, by Milo's reading?

   • The universe began as a blast at one spot in space
   • It shows galaxies' colors
   • The early universe was hot and smooth everywhere
   • It comes from one nearby star
7. 5.

   As the universe expands, what happens to the background's temperature over time, by Noah's reading?

   • It keeps falling
   • It keeps rising
   • It stays at 3,000 K
   • It jumps up and down each year
8. 6.

   Four cards, labeled A to D. Which of these would most weaken the Big Bang model if it were found, by Pia's reading?

   • A galaxy with a large redshift
   • A star clearly older than 13.8 billion years
   • A scientist calling the model just a theory
   • A microwave glow in each direction
9. 7.

   All-sky map of the background with tiny temperature differences. Why do the tiny temperature differences in the background matter, by Ren's reading (NASA)?

   • They are errors made while drawing the map
   • They are nearby stars
   • They show where the explosion happened
   • They were seeds that grew into galaxies
10. 8.

    Hydrogen and helium make up nearly all the atoms in the oldest stars, which have very little iron. What does this support, by Tala's reading?

    • The Big Bang made mostly iron
    • The first stars formed from Big Bang gas, before much iron existed
    • Old stars have used up their iron
    • The oldest stars formed first, from galaxy collisions
11. 9.

    If the universe's 13.8 billion years were one 24-hour day, about how many hours ago did the Sun form (4.6 billion years ago), by Zee's math?

    • A few seconds ago
    • About 16 hours ago
    • About 8 hours ago
    • About 4.6 hours ago
12. 10.

    Three evidence lines pointing to one explanation. Three independent lines of evidence all point to the same model. Why does that matter, by Ari's reading?

    • Independent agreement makes the explanation much stronger
    • It shows the evidence pieces are the same
    • It means the model is just a guess that has not been tested yet
    • One line would be enough