Orbital cycles and ice ages

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Three dials

   Orbit shape, tilt and wobble, each with its cycle.

2. 1.

   Which orbital change runs in a cycle of about 100,000 years, by Ari's reading (NASA)?

   • Eccentricity, the shape of the orbit
   • Earth's daily spin
   • Obliquity, the tilt
   • Precession, the wobble of Earth's axis
3. 2.

   About how long is the tilt (obliquity) cycle, by Bo's reading (NASA)?

   • About 100,000 years
   • About 1 year
   • About 41,000 years
   • About 26,000 years
4. 3.

   About how long is the axial wobble (precession) cycle, by Kira's reading (NASA)?

   • About 26 years
   • About 41,000 years
   • About 100,000 years
   • About 26,000 years
5. 4.

   Earth tilted more and less beside the Sun. What is obliquity, by Jun's reading (NASA)?

   • The direction the wobble points
   • The shape of the orbit
   • The tilt of Earth's axis relative to its orbit
   • Earth's distance from the Sun
6. 5.

   Earth's orbit with January and July marked. NASA: Earth is closest to the Sun around January 3. Why are northern winters cold anyway, by Luz's reading?

   • The tilt has no effect on seasons
   • Earth is farthest from the Sun in January
   • Distance sets the seasons
   • The Northern Hemisphere is tilted away from the Sun then
7. 6.

   NASA: as ice cover grows, it reflects more of the Sun's energy. What does that do, by Pia's reading?

   • It warms Earth
   • It has no effect on temperature
   • It promotes further cooling
   • It speeds up Earth's orbit
8. 7.

   Earth tilted more and less beside the Sun. NASA: a smaller tilt gives cooler summers at high latitudes. What does that allow, by Ren's reading?

   • Ice sheets to melt faster and shrink toward the poles
   • Hotter summers
   • Ice to reflect less sunlight
   • Snow and ice to build up into large ice sheets

9. EPICA Dome C temperature record (NOAA NCEI)

   Years ago	Temperature vs last 1,000 years
   20,000	−9.4 °C
   128,000	+3.4 °C
   140,000	−9.1 °C
   410,000	+1.6 °C
   800,000	−8.9 °C

10. 8.

    Using the EPICA table, how did Antarctica 20,000 years ago compare with the last 1,000 years, by Tala's reading?

    • About 9.4 °C warmer
    • About 94 °C colder
    • About 9.4 °C colder
    • About the same
11. 9.

    Which time in the EPICA table was warmer than the last 1,000 years, by Zee's reading?

    • 140,000 years ago
    • 20,000 years ago
    • 800,000 years ago
    • 128,000 years ago
12. 10.

    How far back does the EPICA Dome C ice-core record reach, by Esme's reading (NOAA)?

    • About 800,000 years
    • About 800 years
    • About 80 million years
    • About 8,000 years