Orbital cycles and ice ages

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Earth's orbit with January and July marked. A classmate says summer comes when Earth is closest to the Sun. Which reply fits NASA, by Esme's reading?

   • No; seasons come from the wobble alone
   • Correct; closest means summer everywhere
   • Correct; the farthest point comes in winter
   • No; Earth is closest around January 3, in northern winter, and tilt sets seasons

2. Read this first

   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

3. 2.

   A student says ice ages come and go over a few centuries. Which reply fits NASA, by Jun's reading?

   • No; for 800,000 years they have cycled about every 100,000 years
   • Correct; each lasts about 100 years
   • Correct; they follow the 11-year sunspot cycle
   • No; they come about once in each 10 million years, far apart in time
4. 3.

   Earth tilted more and less beside the Sun. A student says a bigger tilt helps ice sheets grow. Which reply fits NASA, by Kira's reading?

   • No; larger tilt favors melting, and a smaller tilt lets ice build
   • Correct; a big tilt means cold summers
   • No; ice grows when Earth is farthest from the Sun in northern June
   • Correct; tilt has no effect on ice
5. 4.

   A timeline divided into equal cycles. Hays and colleagues studied 450,000 years (NASA). About how many 41,000-year tilt cycles fit in that span, by Milo's math?

   • About 110
   • About 4.5
   • About 1.1
   • About 11
6. 5.

   Four evidence cards, labeled A to D. Which evidence best supports Milankovitch's idea, by Pia's reading (NASA)?

   • Tilt staying fixed for a million years while the ice sheets came and went
   • One cold winter after a far aphelion
   • Sediment and ice cores show climate swings timed with orbital cycles
   • Ice ages repeating each century

7. 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

8. 6.

   Model data: cold periods come every 100,000 years for the last 800,000 years and every 41,000 years before that. Which cycles match each part, by Ren's reading?

   • The yearly orbit for both parts
   • The 26,000-year wobble for both parts
   • Orbit shape recently; tilt earlier
   • Tilt recently; orbit shape earlier
9. 7.

   Earth's orbit with January and July marked. NASA: about 6.8% more sunlight arrives in January than in July today. As eccentricity keeps shrinking toward a circle, what happens to that difference, by Tala's reading?

   • It stays at 6.8% for good
   • It grows
   • It shrinks
   • It flips the seasons
10. 8.

    Orbit shape, tilt and wobble, each with its cycle. Which summary of Milankovitch cycles fits NASA, by Zee's reading?

    • They change the Sun's brightness each year
    • Orbit shape (about 100,000 years), tilt (41,000) and wobble (26,000) shift sunlight
    • Orbit shape (26,000), tilt (100,000) and wobble (41,000)
    • They set the seasons by distance
11. 9.

    Which summary of how ice ages are paced fits NASA, by Ari's reading?

    • Hotter summers build ice sheets at high latitudes, and the ice warms Earth
    • A larger tilt builds the ice
    • Cooler high-latitude summers let ice build, and bright ice adds cooling
    • Each ice age lasts about 100 years

12. 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

13. 10.

    Which summary of the EPICA Dome C record fits NOAA, by Bo's reading?

    • About 800,000 years of Antarctic temperature, with glacials near −9 °C
    • Glacials warmer than interglacials
    • About 800 years of steady temperature
    • Glacials about 90 °C colder