Philips Atlas of the Universe

THE SOLAR SYSTEM

Uranus

N

Rings

Path of star

as seen from

aircraft

OrbitofMiranda

1966 (1798–1882–1966) 1985 (1817–1901–1985) 2007 (1839–1923–2007) 2030 (1862–1946–2030)

Uranus, 24 August

1991 – a drawing I made

with a magnification

of 1000 on the Palomar

60-inch (152-cm) reflector.

Even with this giant

telescope, no surface

details could be made out;

all that could be seen was

a greenish disk.

Uranus from Hubblein

a view obtained in 1994.

The picture is a composite

of three images taken six

minutes apart. Because the

moons move fairly rapidly,

their positions change

noticeably over a few

minutes, so each appears in

the image as three dots.

PLANETARY DATA – URANUS

Sidereal period 30,684.9 days

Rotation period 17.2 hours

Mean orbital velocity 6.80 km/s (4.22 miles/s)

Orbital inclination 0.773°

Orbital eccentricity 0.047

Apparent diameter max. 3.7”, min. 3.1”

Reciprocal mass, Sun = 1 22,800

Density, water = 1 1.27

Mass, Earth = 1 14.6

Volume, Earth = 1 67

Escape velocity 22.5 km/s (14.0 miles/s)

Surface gravity, Earth = 1 1.17

Mean surface temperature 
214°C

Oblateness 0.24

Albedo 0.35

Maximum magnitude 5.6

Diameter (equatorial) 51,118 km (31,770 miles)

 The changing presentation

of Uranus. Sometimes a pole

appears in the middle of the

disk as seen from Earth;

sometimes the equator is

presented. Adopting the

International Astronomical

Union definition, it was the

south pole which was in

sunlight during the Voyager

2 pass in 1986.

 Discovery of the rings of

Uranus.On 10 March 1977

Uranus occulted the star

SAO 158687, magnitude 8.9,

and observations from

South Africa and from the

Kuiper Airborne Observatory,

flying over the Indian

Ocean, established the

existence of a ring system –

confirmed by subsequent

observations.

Earth

Ariel

Epsilon ring

Cressida

Juliet

Portia

Miranda

Belinda

Puck

star

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