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20 Space

This giant planet has a magnificent system of

shining rings circling its equator. Saturn is the

second largest planet in the Solar

System, and is made mainly

of hydrogen and helium.

WHAT ARE SATURN’S RINGS?

Saturn’s seven rings may look solid, but

in reality they are scattered chunks of rock

and ice. The largest lumps are hundreds of metres

across and the smallest are specks of dust. The rings

may be the broken remains of one or more comets.

WHAT IS TITAN LIKE?

Bigger than the planet Mercury, Titan is Saturn’s

largest moon. Measuring 5,150 km (3,200 miles)

across, it is the second largest moon in the Solar

System. Titan’s temperature is about –180°C (–292°F),

and it is the only moon with a thick atmosphere.

4 TITAN

Although Titan’s icy surface

is hidden under an orange

haze, infrared telescopes, radar,

and a probe that landed on its

surface, have revealed lakes

of liquid ethane and methane.

SATURN

Saturn

1 RINGS OF SATURN

The Voyager probes took stunning pictures of Saturn

(right) in 1980 and 1981. A false-colour image of the

rings (above) shows up the differences between them.

SATURN DATA

Diameter (width) at Equator 120,536 km (74,900 miles)

Average distance from Sun 1,427 million km (887 million miles)

Time to orbit Sun 29.46 years

Time to spin around own axis 10.66 hours

Mass 95 x Earth’s mass

Gravity 0.92 x Earth’s gravity

Cloud-top temperature -140°C (-220°F)

Number of moons at least 62

FIND OUT MORE. Interplanetary Spacecraft 29 • Mercury 18 • Solar System 14

Tilted at 98°, Uranus seems to be spinning on its side.

As it moves in its orbit, first one pole and then the other

points straight at the Sun. Uranus is the third largest

planet, a ringed gas giant with 13 rings.

WHAT ARE URANUS’S MOONS LIKE?

Uranus has at least 27 moons, and most are

tiny. Titania, 1,578 km (981 miles) across, is

the biggest. The smallest, including Trinculo

and Margaret, are about 10 km (6 miles) wide. Many of

the moons are named after Shakespearean characters.

WHO DISCOVERED URANUS?

In 1781, English astronomer William Herschel spied

Uranus through his home-made telescope. It was the

first planet to be discovered with a telescope.

4 RING SYSTEM

Uranus’s 13 rings appear almost

upright because of the planet’s

tilt. The Epsilon ring is the

thickest, 100 km (62 miles) across.

AMAZING MOON MIRANDA 3

Miranda’s surface is a patchwork

of geological features, including

strange grooves, cliffs, and valleys.

URANUS

Uranus

Narrow main rings are

made of dark particles

about 1 m (3 ft) across

Diameter (width) at Equator 51,118 km (31,764 miles)

Average distance from Sun 2,871 million km (1,784 million miles)

Time to orbit Sun 84 years

Time to spin around own axis 17.24 hours

Mass 14.5 x Earth’s mass

Gravity 0.89 x Earth’s gravity

Cloud-top temperature -197°C (-322°F)

Number of moons 27

Infrared false-colour image

from the Hubble Space

Telescope reveals bands

in Uranus’s atmosphere

that do not show

up in ordinary

light

URANUS DATA

FIND OUT MORE. Astronomy 11 • Earth 16 • Solar System 14

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Saturn

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Uranus