What a star's light shows: spectra and color

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   A gas cloud's spectrum shows bright lines at 656.3 and 486.1 nm on a dark background. What is the cloud, by Jun's reading?

   • Hot, thin hydrogen glowing on its own
   • Cool hydrogen gas sitting in front of a bright star
   • Gas that contains no hydrogen
   • A hot, dense solid
2. 2.

   Hydrogen, 656.3, 486.1, 434.0, 410.2; helium, 587.6; sodium, 589.0, 589.6; calcium, 393.4, 396.8. A star shows a dark line at 587.6 nm but none at 589.0 or 589.6 nm. Which element is it, by Kira's reading?

   • Sodium, since 587.6 is close to 589
   • Neither, since dark lines mean missing
   • Helium, not sodium
   • Both sodium and helium
3. 3.

   Luz's friend says dark lines mean a star is missing those elements. Which response is best?

   • Agree: dark means nothing is there
   • Disagree: elements in the outer gas absorb those wavelengths
   • Agree: the elements are hidden in the core
   • Disagree: dark lines are bright lines seen from far away
4. 4.

   Noah's friend says we cannot know what stars are made of without visiting them. Which response is best (NASA)?

   • Agree: we need samples to know
   • Agree: starlight carries no information
   • Disagree: their lines match elements measured in labs
   • Disagree: the color of a star's light alone tells us the elements
5. 5.

   Peak = 2,898,000 nm·K ÷ temperature; peak 1,000 nm. A star's light peaks at 1,000 nm. About what is its surface temperature, by Pia's math?

   • About 2,900 K
   • About 2,898,000,000 K
   • About 29,000 K, since a longer peak means hotter
   • About 345 K
6. 6.

   Peak = 2,898,000 nm·K ÷ temperature; stars at 4,000, 6,000 and 20,000 K. Which of these stars peaks in the ultraviolet: 4,000 K, 6,000 K or 20,000 K, by Ren's math?

   • The 4,000 K star
   • The 20,000 K star, peaking near 145 nm
   • The 6,000 K star, like the Sun
   • No star; their peaks stay in visible light
7. 7.

   The Sun peaks near 502 nm. Another star peaks at 251 nm. How does its temperature compare, by Tala's math?

   • The same as the Sun's
   • About 4 times the Sun's
   • About half the Sun's
   • About twice the Sun's, near 11,500 K
8. 8.

   Star P is blue with strong helium lines. Star Q is yellow with strong sodium and calcium lines. What can Zee say?

   • P lacks sodium, since its strip shows no sodium lines
   • Q is hotter, since it shows more lines
   • P is hotter; each spectrum reveals elements in its outer gas
   • Both are the same temperature
9. 9.

   The Sun's dark calcium lines at 393.4 and 396.8 nm are very strong. What does this show, by Ari's reading?

   • Those lines belong to hydrogen
   • The Sun has no calcium
   • Calcium in the Sun's outer gas glows brightly at those wavelengths
   • Calcium in the Sun's outer gas absorbs those wavelengths
10. 10.

    The same dark-line pattern appears in a lab gas and in a distant star. What is the strongest conclusion, by Bo's reading?

    • The star is the same temperature as the lab
    • The star's gas glows with bright lines
    • The star lacks that element
    • The star's outer gas contains that element