Redshift and the expanding universe

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   A distant galaxy's hydrogen lines sit at longer wavelengths than in the lab. What is this called, by Ari's reading?

   • Blueshift
   • A red-colored galaxy
   • Absorption
   • Redshift
2. 2.

   What does a redshift tell Bo about a galaxy?

   • It is hotter than our galaxy
   • It is made of red stars
   • It is moving toward us
   • It is moving away from us
3. 3.

   A galaxy shows redshift, but in a photo it looks blue-white. Is that possible, by Kira's reading?

   • Yes, but just if it is very close
   • No: blue means it moves toward us
   • No: redshifted galaxies must look red
   • Yes: redshift is about line positions, not color
4. 4.

   Spectrum strip with lab line positions marked and an arrow toward each end. A galaxy is moving toward Earth. Which way are its lines shifted, by Jun's reading?

   • Into the infrared
   • Toward longer, redder wavelengths
   • Toward shorter, bluer wavelengths
   • It does not shift
5. 5.

   NASA predicts the Andromeda galaxy will meet the Milky Way in about 4 billion years. What shift does Andromeda's light show, by Luz's reading?

   • A redshift, like the far galaxies
   • A redshift, since it is far away
   • No shift, since it is a neighbor
   • A blueshift, since it is coming closer

6. Read this first

   Galaxies (model data)

   Galaxy	Distance (Mpc)	Speed away (km/s)
   P	20	1,400
   Q	50	3,500
   R	100	7,000
   S	200	14,000

7. 6.

   What does the table show about farther galaxies, by Noah's reading?

   • Farther galaxies move away slower
   • Nearer galaxies move away fastest
   • Galaxies move at one shared speed
   • Farther galaxies move away faster
8. 7.

   On a graph of speed against distance for these galaxies, what shape do the points make, by Pia's reading?

   • Points showing the Milky Way at the center
   • A straight line rising to the right
   • A line falling to the right
   • A flat, level line
9. 8.

   Every galaxy far away seems to move away from the Milky Way. Does that put us at the center, by Ren's reading?

   • No: the far galaxies are coming closer
   • Yes: galaxies flee from our galaxy
   • Yes: we are at the center of the expansion
   • No: every galaxy would see the same thing
10. 9.

    Hydrogen's lab line is at 656.3 nm. In a galaxy it sits at 662.9 nm. By how much has it shifted, by Tala's math?

    • 1,319.2 nm
    • 6.6 nm toward shorter wavelengths
    • 6.6 nm toward longer wavelengths
    • 0.6 nm
11. 10.

    Speed ≈ z × 300,000 km/s; z = 0.01. For small redshifts, speed ≈ z × 300,000 km/s. A galaxy has z = 0.01. About how fast is it moving away, by Esme's math?

    • About 3,000 km/s
    • About 0.01 km/s
    • About 300 km/s
    • About 30,000,000 km/s