What meteorites, Moon rocks and ancient crystals tell us

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Table, Sample ages (USGS), with columns Sample, Age (billion years)

   Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

2. 1.

   Order the samples from oldest to youngest, by Bo's reading.

   • Meteorites, Moon rocks, zircons, Earth's oldest rocks
   • Earth's oldest rocks, zircons, Moon rocks, meteorites
   • Moon rocks, Earth rocks, meteorites, zircons
   • Zircons, meteorites, Earth rocks, Moon rocks
3. 2.

   About how much older are the meteorites (about 4.56) than Earth's oldest rocks (4.03 billion years), by Esme's math?

   • About 530 million years
   • About 53 years
   • About 5.3 billion years
   • About 8.6 billion years
4. 3.

   Earth is about 4.54 billion years old, yet its oldest rocks are 4.03 billion. Why the gap, by Jun's reading (USGS)?

   • Plate tectonics has recycled the earliest rocks
   • Earth's first rocks were meteorites that flew back into space
   • The dates must be wrong
   • Earth formed 4.03 billion years ago
5. 4.

   A sample has 1/4 of its parent isotope left. The half-life is 700 million years. About how old is it, by Kira's math?

   • About 700 million years
   • About 1.4 billion years
   • About 175 million years
   • About 2.1 billion years
6. 5.

   A sample has 1/8 of its parent left, with a half-life of 1.3 billion years. About how old is it, by Luz's math?

   • About 10.4 billion years
   • About 3.9 billion years
   • About 1.3 billion years
   • About 2.6 billion years
7. 6.

   USGS says dating uses half-lives from 700 million to more than 100 billion years. Why are such long half-lives useful for these samples, by Milo's reading?

   • Long half-lives stop decaying
   • Enough parent is still left to measure after billions of years
   • Short half-lives would be more accurate for old rocks
   • They measure how far meteorites traveled
8. 7.

   Before Apollo, some thought the Moon was captured or formed beside Earth. Why did those ideas fall out of favor, by Noah's reading (NASA)?

   • Apollo found the Moon had no rocks
   • Apollo samples pointed to a large impact
   • The capture idea was proved by Apollo
   • The Moon turned out to be younger than Earth by billions of years

9. Table, Sample ages (USGS), with columns Sample, Age (billion years)

   Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

10. 8.

    The Moon's oldest rocks (4.4–4.5 billion years) are much older than most of Earth's. Why, by Ren's reading (USGS)?

    • The Moon formed long before Earth
    • The Moon has no plate tectonics to recycle them
    • Earth's rocks are older, but they are buried too deep to find
    • Moon rocks are meteorites
11. 9.

    Most meteorites that fall are stony, but most found long after falling are irons (NASA). Why, by Zee's reading?

    • Irons are younger
    • Iron meteorites fall more often
    • Irons are heavier and easier to tell from Earth rocks
    • Stony meteorites come from the Sun

12. Table, Sample ages (USGS), with columns Sample, Age (billion years)

    Meteorites, 4.53 to 4.58; oldest Moon rocks, 4.4 to 4.5; oldest zircon crystals (Western Australia), 4.3 to 4.4; oldest Earth rocks (Acasta Gneiss, Canada), 4.03.

13. 10.

    On a timeline where 1 cm stands for 100 million years, how far apart are the meteorite age (about 4.56) and the zircon age (about 4.4 billion), by Ari's math?

    • About 1.6 cm
    • About 44 cm
    • About 0.16 cm
    • About 16 cm