How gravity holds the solar system together

Grade 6 Science Worksheet

Circle the best answer.

1. Read this first

   Use this

   Table (NASA Planetary Fact Sheet), with columns Planet, Distance (millions of km) and Orbit time (days), distance from the Sun and orbit time: Mercury 57.9 million km, 88.0 days; Earth 149.6 million km, 365.2 days; Mars 228.0 million km, 687.0 days; Jupiter 778.5 million km, 4,331 days.

2. 1.

   Bo reads the NASA table of orbit times. What pattern does it show?

   • Bigger planets orbit faster
   • Each planet takes one Earth year
   • Planets farther from the Sun take longer to orbit
   • Farther planets orbit faster
3. 2.

   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?

   • About half a year, since it is farther
   • Exactly one year
   • About 1.9 years
   • About 6.9 years
4. 3.

   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?

   • The planets share one speed
   • Farther planets move faster
   • Bigger planets move faster
   • Closer planets move faster in their orbits
5. 4.

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

6. Use this

   Orbit diagram from above, not to scale:

7. 5.

   Earth moves about 29.8 km every second around the Sun. What keeps that fast motion bent into an orbit, says Milo?

   • The Sun's gravity pulling toward the center
   • Nothing; Earth would orbit anyway
   • Its speed alone makes it curve
   • The Moon pushes it around
8. 6.

   Imagine Earth suddenly stopped moving sideways along its orbit. What would the Sun's gravity do, as Pia predicts?

   • Keep Earth orbiting just as before
   • Push Earth away from the Sun
   • Pull Earth straight toward the Sun
   • Nothing; Earth would stay put
9. 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
   • It settles into orbit
   • The air pushes it away into space
10. 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
11. 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 230 years
    • The Sun stays still; it does not orbit
    • About 230 to 250 million years
    • About one year
12. 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?

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