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

   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 63 AU
   • About 0.000016 AU
   • About 63,000 AU
   • About 9.46 trillion AU
4. 3.

   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?

   • 100 parsecs, since a small shift means near
   • 10 parsecs, about 33 light-years
   • 0.1 parsecs
   • 10 light-years
5. 4.

   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 77 parsecs
   • About 1.3 parsecs
   • About 0.77 parsecs
   • About 1.3 light-years
6. 5.

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

   • Earth to the Moon: about 2.6 light-years
   • Sun to Proxima Centauri: about 268,770 parsecs
   • Sun to Saturn: about 9.6 AU
   • Across the Milky Way: about 100,000 AU
7. 6.

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

   • Light-years tell how old stars are
   • A light-year is smaller than a kilometer
   • Kilometers cannot be used off Earth
   • Kilometer values for stars are enormous
8. 7.

   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 4.25 light-years
   • About 268,770 light-years
   • About 17 billion light-years
   • About 4.25 AU
9. 8.

   9,460,000,000,000 km. How is 9,460,000,000,000 km (about 1 light-year) written in scientific notation, by Tala's reading?

   • 9.46 × 10⁹ km
   • 9.46 × 10¹² km
   • 9.46 × 10¹⁵ km
   • 94.6 × 10¹² km

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 2.7 × 10⁵ times
    • About 6.0 × 10²¹ times
    • About 2.7 × 10²¹ times
    • About 5 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