Kepler's three laws of planetary motion

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   The orbit diagram marks point A (the ellipse's center), B (a focus) and C (a point on the curve). Where is the Sun, by Bo's reading?

   • A, the center
   • Outside the ellipse
   • C, on the orbit
   • B, a focus

2. Read this first

   Orbits (NASA Planetary Fact Sheet)

   Planet	a (AU)	T (years)	e
   Mercury	0.387	0.241	0.206
   Earth	1.000	1.000	0.017
   Mars	1.524	1.881	0.094
   Jupiter	5.20	11.86	0.049

3. 2.

   Which planet in the table has the most stretched orbit, by Kira's reading?

   • Mars, e = 0.094
   • Earth, e = 0.017
   • Mercury, e = 0.206
   • Jupiter, e = 0.049
4. 3.

   two shaded slices of equal area. What does Kepler's second law say a line from the Sun to a planet does, by Jun's reading (NASA)?

   • Sweeps equal angles in equal times
   • Sweeps larger areas when far away
   • Sweeps equal areas in equal times
   • Sweeps equal distances in equal times
5. 4.

   Orbit diagram with perihelion and aphelion marked. Where in its orbit does a planet move fastest, by Luz's reading?

   • Halfway between the two
   • Closest to the Sun, at perihelion
   • Farthest from the Sun, at aphelion
   • At the same speed everywhere

6. Orbits (NASA Planetary Fact Sheet)

   Planet	a (AU)	T (years)	e
   Mercury	0.387	0.241	0.206
   Earth	1.000	1.000	0.017
   Mars	1.524	1.881	0.094
   Jupiter	5.20	11.86	0.049

7. 5.

   Which planet in the table takes longest to orbit the Sun, by Noah's reading?

   • They each take one year
   • Mercury, the closest
   • Jupiter, the farthest out
   • Mercury, since it moves fastest
8. 6.

   Mars orbits at 1.524 AU. What is its orbital period in the table, by Pia's reading?

   • 0.53 years, shorter than Earth's
   • 1.881 years
   • 3.54 years, its distance cubed
   • 1.524 years, the same as its distance
9. 7.

   Four equation cards, labeled A to D. Which equation is Kepler's third law, with T in years and a in AU, by Ren's reading?

   • T² = a³
   • T³ = a²
   • T × a = 1
   • T = a

10. Mercury (NASA)

    Point	Distance (million km)
    perihelion	46.0
    aphelion	69.8

11. 8.

    NASA lists Mercury's perihelion as 46.0 and its aphelion as 69.8 million km. By how much does its distance from the Sun change, by Tala's math?

    • 23.8 million km
    • 0 km, since its orbit is a circle
    • 115.8 million km
    • 57.9 million km

12. Earth (NASA)

    Point	Distance (million km)
    perihelion	147.1
    aphelion	152.1

13. 9.

    Earth is closest to the Sun in early January (NOAA). Why is January not summer in the Northern Hemisphere, by Zee's reading?

    • The 5 million km change sets the seasons
    • Seasons come from Earth's tilt, not its distance
    • Earth's orbit is a perfect circle
    • January is summer everywhere on Earth
14. 10.

    Earth's orbital eccentricity is 0.017 (NASA). What does that tell Esme about the shape of the orbit?

    • It is stretched enough to cause the seasons
    • It is a perfect circle
    • It is very stretched, like a comet's
    • It is very nearly a circle