Download Giant Planets

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Saturn was the first planet known to have rings. A planetary ring is a wide, flat zone of small particles that orbit a
planet. All four gas giants have rings around their equators.
Saturn’s rings are made of chunks of water ice the size of a
building or smaller. Larger chunks, considered to be tiny
moons, orbit within the rings. Saturn’s main rings are very
bright. The outermost ring is three times as wide as the planet,
but it is usually too faint to see. Saturn’s rings have bright and
dark stripes that change over time.
gap between
rings
shadow
You can use Saturn’s rings to see the planet’s seasons. Like Earth’s
axis of rotation, Saturn’s axis is tilted. The angle is 27 degrees. When the
image on this page was taken, sunlight shone more on the northern
hemisphere, so the north side of the rings was bright. The shadow of
the rings fell on the southern hemisphere. Winter started in Saturn’s
northern hemisphere in May 2003 and will last more than seven Earth
years. Saturn is almost ten times farther from the Sun than Earth is, so
Saturn takes almost 30 Earth years to go around the Sun once.
Sunlight shines from the
upper right of this image.
The rings cast shadows
on Saturn‘s clouds.
Giant Planets
Why do Saturn’s rings seem to change size?
SKILL FOCUS
Observing (8.4.e)
PROCEDURE
1
Poke the stick through the plate and cut off the plate’s rim. Shape the clay
onto both sides of the plate to make a model of a planet with rings.
2 Model Saturn’s orbit for your partner. Stand between your partner and the
classroom clock. Point one end of the stick at the clock. Hold the model at
the same height as your partner’s eyes. Have your partner watch the model
with just one eye open.
3 Move one step counterclockwise around your partner and
point the stick at the clock again. Make sure the model is as
high as your partner’s eyes. Your partner may need to turn to
see the model.
MATERIALS
•
•
•
•
ice-cream stick
disposable plate
scissors
clay
TIME
20 minutes
4 Continue taking steps around your partner and pointing the
stick at the clock until you have moved the model all the
way around your partner.
5 Switch roles with your partner and repeat steps 2, 3, and 4.
WHAT DO YOU THINK?
• How did your view of the rings change as the model planet
changed position?
• How many times per orbit do the rings seem to vanish?
CHALLENGE How do Saturn’s axis and orbit compare with
those of Earth?
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