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?

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

   Earth 365.2 days; Neptune 59,800 days. Neptune takes about 59,800 days to orbit the Sun (NASA). About how long is one Neptune year, as Jun works it out?

   • About 16 Earth years
   • About 164 Earth years
   • About 1 Earth year
   • Less than an Earth year, since it is farther
5. 4.

   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?

   • Closer planets move faster in their orbits
   • The planets share one speed
   • Farther planets move faster
   • Bigger planets move faster
6. 5.

   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

7. Use this

   Orbit diagram from above, not to scale:

8. 6.

   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
   • Its speed alone makes it curve
   • Nothing; Earth would orbit anyway
   • The Moon pushes it around
9. 7.

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

   • Nothing; Earth would stay put
   • Pull Earth straight toward the Sun
   • Push Earth away from the Sun
   • Keep Earth orbiting just as before
10. 8.

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

    • It floats in place, since gravity stops
    • It settles into orbit
    • It falls back to Earth
    • The air pushes it away into space
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 one year
    • About 230 to 250 million years
    • The Sun stays still; it does not orbit
    • About 230 years
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?

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