The evidence for the Big Bang

Grade 9 Science Worksheet - Challenge Me

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.

   Which list of evidence supports the Big Bang model without relying on any one method, by Jun's reading?

   • Redshifts of one galaxy measured three times by one telescope
   • The Sun's age, Earth's age and the Moon's age
   • Redshifts, the microwave background and light-element amounts
   • Starlight, sunlight and moonlight
3. 2.

   Light from very distant galaxies left them billions of years ago. Why does that let astronomers test the Big Bang model, by Kira's reading?

   • Distant galaxies are where the explosion was
   • Far away means long ago, so early times can be seen
   • Distant light shows what the universe looks like today
   • Old light is the microwave background itself
4. 3.

   Luz's friend says the Big Bang was an explosion at one spot in empty space. Which response is best?

   • Disagree: the universe has stayed the same
   • Agree: debris flew out from one center
   • Disagree: space itself expanded everywhere from a hot, dense state
   • Agree: the Milky Way is near the blast site
5. 4.

   Three evidence lines pointing to one explanation. Milo's cousin says the Big Bang is just a theory, meaning nobody really knows. Which response is best?

   • Agree: it has not been tested
   • Disagree: theories do not change
   • Disagree: a scientific theory is backed by many tested observations
   • Agree: theories are guesses that scientists make before they test anything
6. 5.

   Noah's friend says the microwave background is just the glow of all the stars. Which response is best (NASA)?

   • Agree: starlight adds up to it
   • Agree: it comes from the stars of the Milky Way galaxy
   • Disagree: it was released before any stars existed
   • Disagree: it comes from Earth's atmosphere
7. 6.

   The background light set off about 380,000 years after the start. What fraction of the universe's 13.8 billion years is that, by Pia's math?

   • About 3%
   • About 0.003%
   • About 30%
   • About 0.3%
8. 7.

   If the universe were much older than 13.8 billion years, what would the background's temperature be today, by Ren's reading?

   • Hotter than 2.7 K
   • About 3,000 K
   • Exactly 2.7 K
   • Colder than 2.7 K
9. 8.

   Four prediction cards, labeled A to D. Which prediction does the Big Bang model make about very distant, early galaxies, by Zee's reading?

   • They should sit at the center of the universe
   • They should hold fewer heavy elements
   • They should show blueshifts
   • They should hold more iron than the Sun

10. Background temperature (NASA, ESA)

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

11. 9.

    The background was about 3,000 K at release and is 2.7 K now. Its wavelengths have stretched by about what factor, by Ari's math?

    • About 1,100 times longer
    • About 3 times longer
    • Unchanged, since light keeps its wavelength
    • About 1,100 times shorter
12. 10.

    Four cards, labeled A to D. Which observation would scientists need before changing the Big Bang model, by Bo's reading?

    • Strong, repeated evidence that disagrees with its predictions
    • Someone's opinion that it seems strange
    • A galaxy with a redshift
    • A single unchecked measurement