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?

   • The Sun's age, Earth's age and the Moon's age
   • Redshifts, the microwave background and light-element amounts
   • Starlight, sunlight and moonlight
   • Redshifts of one galaxy measured three times by one telescope
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 light shows what the universe looks like today
   • Old light is the microwave background itself
   • Distant galaxies are where the explosion was
   • Far away means long ago, so early times can be seen
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?

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

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

   • Disagree: it comes from Earth's atmosphere
   • Disagree: it was released before any stars existed
   • Agree: starlight adds up to it
   • Agree: it comes from the stars of the Milky Way galaxy
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 30%
   • About 0.3%
   • About 0.003%
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?

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

   The Planck mission gives about 13.8 billion years, and the oldest stars measured are a little younger. Why does that fit, by Tala's reading?

   • Stars formed after the universe began, so they must be younger
   • It shows the universe's age is just a rough guess with no support
   • Stars should be older than the universe
   • It shows the stars made the background

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

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

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