How gravity holds the solar system together

Grade 6 Science Worksheet

Circle the best answer.

1. 1.

   Earth 365.2 days; Mars 687.0 days. Mars takes 687.0 days to orbit the Sun. About how many Earth years is that, by Esme's math?

   • Exactly one year
   • About 6.9 years
   • About 1.9 years
   • About half a year, since it is farther
2. 2.

   Mercury 47.4 km/s; Earth 29.8 km/s; Jupiter 13.1 km/s; Neptune 5.4 km/s. Kira reads the NASA table of orbit speeds. What does the table show?

   • Bigger planets move faster
   • The planets share one speed
   • Farther planets move faster
   • Closer planets move faster in their orbits
3. 3.

   Mercury 47.4 km/s; Neptune 5.4 km/s. Mercury races around the Sun at 47.4 km/s, while Neptune moves at 5.4 km/s. Why the big difference, by Luz's reasoning?

   • Wind in space pushes Neptune back
   • Mercury's spin pushes it along like an engine
   • Farther planets should move faster, so the table is wrong
   • The Sun's pull is much stronger close in
4. 4.

   “Orbit diagram from above, not to scale:” Earth moves about 29.8 km every second around the Sun. What keeps that fast motion bent into an orbit, says Milo?

   • Its speed alone makes it curve
   • The Moon pushes it around
   • The Sun's gravity pulling toward the center
   • Nothing; Earth would orbit anyway
5. 5.

   Which two things together make an orbit, according to Noah's notes?

   • A pull toward the center by itself
   • A push from behind and solar wind
   • A pull toward the center and fast sideways motion
   • Fast sideways motion by itself
6. 6.

   “Orbit diagram from above, not to scale:” Imagine Earth suddenly stopped moving sideways along its orbit. What would the Sun's gravity do, as Pia predicts?

   • Pull Earth straight toward the Sun
   • Nothing; Earth would stay put
   • Push Earth away from the Sun
   • Keep Earth orbiting just as before
7. 7.

   A small science payload is launched straight up a few hundred kilometers with no sideways speed. What happens next, by Ren's reasoning?

   • It falls back to Earth
   • It floats in place, since gravity stops
   • The air pushes it away into space
   • It settles into orbit
8. 8.

   What holds the billions of stars of the Milky Way together, as Tala reads?

   • The Sun's gravity alone
   • Nothing; stars drift freely
   • Light holding them in place
   • Gravity
9. 9.

   Drawing of a spiral galaxy seen from above, with the Sun's position marked and an orbit arrow around the center. The Sun orbits the center of the Milky Way. About how long does one trip take, according to NASA and Zee's notes?

   • About one year
   • The Sun stays still; it does not orbit
   • About 230 to 250 million years
   • About 230 years
10. 10.

    Drawing of a spiral galaxy seen from above, with a bar labeled about 100,000 light-years. The Milky Way is about 100,000 light-years across. What does gravity do at that huge size, by Ari's reading?

    • It still holds the whole galaxy together
    • The galaxy is held together by wind
    • Gravity works just near planets
    • Gravity stops at the edge of the solar system