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
   • Farther 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 1.9 years
   • About half a year, since it is farther
   • Exactly one year
   • 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 164 Earth years
   • About 1 Earth year
   • About 16 Earth years
   • Less than an Earth year, since it is farther
5. 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
   • Nothing; Earth would orbit anyway
   • The Sun's gravity pulling toward the center
   • The Moon pushes it around
6. 5.

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

   • A pull toward the center by itself
   • A pull toward the center and fast sideways motion
   • A push from behind and solar wind
   • Fast sideways motion by itself
7. 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?

   • Nothing; Earth would stay put
   • Keep Earth orbiting just as before
   • Pull Earth straight toward the Sun
   • Push Earth away from the Sun
8. 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 settles into orbit
   • The air pushes it away into space
   • It floats in place, since gravity stops
9. 8.

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

   • The Sun's gravity alone
   • Light holding them in place
   • Nothing; stars drift freely
   • Gravity
10. 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 years
    • About 230 to 250 million years
11. 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