How the solar system formed

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   a cloud, a spinning disk, young planets, today's solar system. How did the solar system begin, by Ari's reading (NASA)?

   • A cloud of gas and dust collapsed under its own gravity
   • It formed during the first few minutes after the Big Bang began
   • A planet broke apart into pieces
   • The Sun spun off the planets later
2. 2.

   Timeline ruler in billions of years. About when did the solar system form, by Bo's reading (NASA)?

   • About 13.8 billion years ago, with the universe
   • About 4.6 million years ago
   • About 4.6 billion years ago
   • About 4,600 years ago
3. 3.

   “then” Why did the collapsing cloud flatten into a disk, by Jun's reading (NASA)?

   • It spun faster as it shrank and flattened
   • Wind from Earth pushed it flat
   • It cooled into a flat sheet of rock
   • It stopped spinning and spread out
4. 4.

   Why do all eight planets orbit in nearly the same flat plane, by Luz's reading?

   • They broke off a larger planet
   • They were captured one at a time from space
   • They formed from one flat, spinning disk
   • The cloud did not spin
5. 5.

   Orbit diagram with the disk's spin direction marked. In which direction do the planets orbit the Sun, by Milo's reading?

   • Inner one way, outer the other
   • Each in a random direction
   • All the same way, the way the disk spun
   • They do not orbit; the Sun circles them
6. 6.

   Disk with a hot inner zone and a cold outer zone. Why did rocky planets form near the Sun, by Pia's reading (NASA)?

   • Ice was most common near the Sun
   • Only rock could withstand the heat near the young Sun
   • The Sun threw rocks out to them
   • Gas was heavier and sank to the middle
7. 7.

   Orbit diagram with Uranus and Neptune marked. What are Uranus and Neptune called, by Ren's reading (NASA)?

   • Terrestrial planets
   • Dwarf planets
   • Gas giants, like Jupiter
   • Ice giants
8. 8.

   What are asteroids, by Tala's reading (NASA)?

   • Pieces formed in just the last few thousand years or so
   • Rocks thrown out by Earth's volcanoes
   • Rocky leftovers from the solar system's formation
   • Pieces of a planet that blew apart
9. 9.

   Sun, inner planets, Jupiter and an asteroid belt. Where are most asteroids found, by Zee's reading (NASA)?

   • Between Mars and Jupiter
   • Inside Mercury's orbit
   • Between Earth and the Moon
   • Where a lost planet broke up
10. 10.

    Orbit diagram with the Kuiper Belt beyond Neptune. What does NASA say the icy worlds of the Kuiper Belt, beyond Neptune, are, by Esme's reading?

    • New worlds forming today
    • Pieces broken off Neptune
    • Icy leftovers from the solar system's formation
    • Rocky planets like Earth