Astronomical units, light-years and parallax

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Distance from the Sun (NASA Planetary Fact Sheet)

   Planet	Distance (million km)
   Earth	149.6
   Jupiter	778.5

2. 1.

   Jupiter is about 778.5 million km from the Sun (NASA). About how many AU is that, using 1 AU ≈ 149.6 million km, by Bo's math?

   • About 116,000 AU
   • About 0.19 AU
   • About 5.2 AU
   • About 5.2 light-years
3. 2.

   Note: light speed 299,792 km/s. Neptune is about 4,515 million km from the Sun (NASA). About how long does sunlight take to reach it, at 299,792 km/s, by Esme's math?

   • About 4.2 minutes
   • About 4.2 hours
   • About 15 minutes
   • About 4.2 years
4. 3.

   1 light-year ≈ 9.46 trillion km; 1 AU ≈ 149.6 million km. About how many AU fit in 1 light-year (9.46 trillion km ÷ 149.6 million km), by Jun's math?

   • About 0.000016 AU
   • About 63,000 AU
   • About 9.46 trillion AU
   • About 63 AU
5. 4.

   Distance (parsecs) = 1 ÷ parallax (arcseconds); 1 parsec ≈ 3.26 light-years; parallax 0.10. A star's parallax is 0.10 arcseconds. How far away is it, by Kira's math?

   • 0.1 parsecs
   • 100 parsecs, since a small shift means near
   • 10 light-years
   • 10 parsecs, about 33 light-years
6. 5.

   Distance (parsecs) = 1 ÷ parallax (arcseconds); parallax about 0.77. Proxima Centauri's parallax is about 0.77 arcseconds. About how far is it in parsecs, by Luz's math?

   • About 1.3 parsecs
   • About 77 parsecs
   • About 0.77 parsecs
   • About 1.3 light-years
7. 6.

   Four distance cards, labeled A to D. Which distance is given in a sensible unit, by Noah's reading?

   • Across the Milky Way: about 100,000 AU
   • Sun to Saturn: about 9.6 AU
   • Sun to Proxima Centauri: about 268,770 parsecs
   • Earth to the Moon: about 2.6 light-years
8. 7.

   Why do astronomers give star distances in light-years instead of kilometers, by Pia's reading?

   • A light-year is smaller than a kilometer
   • Light-years tell how old stars are
   • Kilometer values for stars are enormous
   • Kilometers cannot be used off Earth
9. 8.

   1 light-year ≈ 63,241 AU; Proxima Centauri about 268,770 AU. NASA gives Proxima Centauri's distance as about 268,770 AU. With about 63,241 AU per light-year, how many light-years is that, by Ren's math?

   • About 17 billion light-years
   • About 4.25 light-years
   • About 4.25 AU
   • About 268,770 light-years

10. Distances (NASA)

    Object	Distance (km)
    Sun	1.50 × 10⁸
    Proxima Centauri	4.02 × 10¹³

11. 9.

    Proxima Centauri is about 4.02 × 10¹³ km away; the Sun is about 1.50 × 10⁸ km away. About how many times farther is Proxima, by Zee's math?

    • About 5 times
    • About 2.7 × 10⁵ times
    • About 2.7 × 10²¹ times
    • About 6.0 × 10²¹ times
12. 10.

    c = 299,792,458 m/s (NIST); 1 year ≈ 3.156 × 10⁷ s. NIST gives light speed as 299,792,458 m/s; a year (365.25 days) is about 3.156 × 10⁷ s. About how many meters is a light-year, by Ari's math?

    • About 9.5 m
    • About 9.46 × 10⁵⁶ m
    • About 9.46 × 10¹² m
    • About 9.46 × 10¹⁵ m