Although Uranus is sometimes visible to the naked eye at magnitude 5.5, it
was unknown until the eighteenth century. It was discovered with a telescope
larger than anyone else's by an organist and amateur astronomer, Sir William
Herschel (b. 15 November 1738, Hanover; d. 25 August 1822, Slough), from the
garden of his home at 19 New King Street, Bath. It was found at 24° 27'
Gemini on 13 March 1781 between 2200 hr and 2300 hr LT, and was noted to be an
unusual star "visibly larger than the rest". It was at first taken
by him to be a comet. The following month, 26 April, when he made his 'An
Account of a Comet' report at the Royal Society he said that the object was in
fact disc-shaped and in motion against the stars, and its true nature was
gradually realised. It was announced as a planet by Lexell in St Petersburg
and La Place, France, in 1982, and Herschel published the information in
England on 7 November 1782. It was the first planet to be discovered since
prehistoric times, particularly startling since until then the solar system
was thought only to extend to the limit of Saturn's orbit. The discovery made
Herschel's name and he was able to become a professional astronomer. Although
scientists had observed the 'star' on at least 22 occasions previously, none
had realised its significance.
At the time Herschel called the planet Georgium Sidus (George's Star) after
his sovereign patron, George III. The French preferred the name Herschel,
presumably not wishing to deify an English ruler, and other suggestions
included Hypercronius. Johann Elert Bode had suggested the name Uranus in the
year of its discovery, and this eventually became accepted by the 1790s after
support from John Couch Adams.
Uranus is twice as far from the Sun as Saturn, at an average distance of 1,783
million miles. It takes 84.01 years to complete its solar circuit, travelling
4° per year as viewed from Earth. Its orbit has an eccentricity of 0.0472.
Uranus has a diameter of 29,000 miles, so is about four times larger than
Earth, or half the size of Saturn, and has a fast rotation period of 17 14.4'
hours, explaining its flattened shape. Its atmosphere consists of hydrogen,
helium, methane and ammonia surrounding a core of ice and rock, with a
temperature of -200°C and no strong internal heat source. One area of its
surface emits a peculiar ultra-violet glow. It has been found to have an
unusually high axial inclination of 97° 52'. It is technically retrograde,
with each pole pointing alternately towards the Sun. Unlike all the other
planets, its axis is virtually in the plane of its orbit, so twice in each
orbit of the Sun the axis is at right angles to the direction of the Sun. The
reason for its axial tilt is not known. It has been posited that it was struck
by a massive body and knocked sideways, though this would not explain why its
moons move virtually in its equatorial plane. Earth, Mars, Saturn and Neptune
have an axial tilt of between 23 to 29 degrees.
Dr Antonio Brunini suggested in 1993 that Uranus had a change of orbit in June
1897, equal to a speed of 100 ft per hour. This would have been due to running
into a large object of at least 600 miles across, which fell from the Kuiper
belt, and this would account for the anomalies of its orbit.
Voyager 2 by-passed Uranus on 24 January 1986 and established that it has a
reasonably strong magnetic field, but its magnetic axis is unaccountably
inclined to the rotational axis by nearly 60° and is perceptibly offset from
the centre of the globe. Voyager 2 also confirmed Uranus's ring system, first
discovered in 1977 during the occultation of the star SAO 158687. These eleven
rings surrounding its equator are not circular and not all symmetrical,
wobbling like an unbalanced wheel, and they are dark, not light like Saturn's,
containing rock, not water-ice. The rings may be young and impermanent
features of the Uranian system. Uranus also has the brightest clouds in the
outer Solar System.
Uranus and Neptune are conjunct every 171 to 171.403 years, and the first
contact of the recent conjunction occurred at 19° Capricorn, first on 2nd
February 1993, then on 20 August 1993, and finally on 24 October, again at the
same degree. Uranus is conjunct with Pluto every 254.280 years. The last of
these began on 9 October 1965 at 17° Virgo. In 2007 the Sun will shine
directly above Uranus' equator, a Uranian mid-summer which will be accompanied
by raging, violent storms, with clouds of condensing crystal methane.
The glyph for Uranus derives from its original name of Herschel, the 'H'
surmounting the circle of spirit. The two semicircles denote the soul of man
and the divine soul of divine manifestation, each linked to the other by the
cross of matter. Television is associated with Uranus and the first television
aeriels resemble this symbol. The make-up of Uranus is largely identified with
that of the French emperor Napoleon Bonaparte (b. 15 August 1769, 0952 hr LMT,
Ajaccio, Corsica; d. 5 May 1821 in exile, St Helena). His domination of the
Western world coincided with the assimilation of the newly discovered planet
into the astrological realms. His new ideas were considered an embodiment of
the new 'star', and the increased importance of Aquarius, which Uranus was
ultimately deemed to co-rule, dates from this period.
Its mythological name was derived from the existing series of planets' names:
Saturn was the father of Jupiter, and Uranus was the father of Saturn (Kronos).
In Greek myth he is Ouranos, the primal god of heaven (not represented by a
physical body), who generated the physical universe when he mated with his
mother-sister Gaia (Rhea), the earth goddess, and produced the race of Titans
and giants. Eventually he was overthrown and castrated by his son Kronos. To
the Hindus he is the great god Varuna, "the Universal encompasser, the
all embracer...Space, the maker of Heaven and Earth, since both manifested out
of his seed."
Even before its discovery astrologers had referred to a hypothetical
extra-saturnine planet which they called Ouranos. Uranus is the first of three
new planets added to the traditional seven of the ancient astrological model,
the others being Neptune and Pluto. The discovery of Uranus challenged the
astrological tradition of thousands of years, that the seven planets formed an
absolute cosmic structure. The known solar system was suddenly doubled in
size, and the ancient seven-planet model had been demolished.
The discovery of Uranus is seen as being linked to the evolution of modern
consciousness; new technology, new understanding, a time of Enlightenment. At
the time of Uranus's discovery the French and American Revolutions were under
way, as was the Industrial Revolution, and electricity was being harnessed (Galvani's
research into the electric current was published a decade later), paving the
way for the aeroplane, radio and television. The democratic rights of the
individual were also being realised for the first time.
Uranus the Magician is seen as a higher octave of Mercury, a planet of change,
marking social or personal revolutions and disruptions. When working
beneficially it can be regarded as magnetic, original, unconventional and
reforming; but when over-stretched it can lapse into mere eccentricity,
pointless rebellion, violence and crime. Its associations with eccentricity
were seemingly astronomically justified by Voyager's discoveries of its
large-scale axial and rotational anomalies.
The first astrologer to confirm the destructive and erratic nature of the
planet, by direct observation of its transits, was the eccentric astrologer
John Varley, a friend of William Blake.
Recently, Uranus has come to be regarded as the ruler of Aquarius, partially
displacing the traditional ruler, Saturn. It is exalted in Scorpio, in fall in
Taurus, and in its detriment in Leo. In esoteric astrology, Uranus rules
Libra. Despite its associations with intuition, Uranus is essentially a
masculine planet, applying to left-brain functions. However, its connections
with Mercury could suggest the embodiment of some feminine principles.
Since Uranus spends approximately seven years in each sign the result is a
mini-generation of individuals, forming a unique Uranus-group. The rings of
Uranus link with those of Jupiter and Saturn to form a subtle realm in which
insight and perception are developed, and where responsibilities for actions
based on these perceptions are sensed.
Uranus signifies our sense of originality; the desire for freedom and
independence; self-liberation; self-reliance; to come to a limit and then
transcend it; our wilfulness and craving for novelty and change; the hankering
after the new at the expense of the old; the urge to be different; the need to
express our own individuality; the rejection of the commonplace and familiar;
our ability for self-discovery and awareness; free enterprise; autonomy;
inter-counter dependence; the dependence needed to get to independence; the
need to listen to our own ego.
Uranus has little to do with its mythological namesake, but more closely
resembles the rebel Titan, Prometheus, who helped overthrow Kronos (Saturn)
and tricked Zeus (Jupiter).
THE MOONS OF URANUS
Five Uranian moons were known to exist prior to the Voyager 2 mission. Ten
new satellites were then found, all in closer orbit to Uranus than those
previously known. Two more were confirmed in 1997 and 1 in 1999, and by 2003
the total had reached twenty-two.
In October 2003 astronomers confirmed five new moons, all rather small. Each
is around 6 miles across. With these additions, Uranus now has 27 moons in total, ranking it
third, behind Jupiter and Saturn.
Cordelia is the nearest to the planet at a distance of 30,740 miles,
and is the smallest with a diameter of 16 miles. It falls within the ring
system. Cordelia and Ophelia, the next in the series, are the shepherd
satellites of Uranus's ring. Bianca, Cressida, Desdemona,
Juliet, Portia, Rosalind and Belinda are the next,
with Puck completing the ten as the largest, with a diameter of 96
miles and a distance of 53,438 miles from Uranus. Puck was the first of these
to be discovered, on 30 December 1985, and Voyager 2 was able to photograph it
at close approach on 24 January 1986. Portia had by then been found, on 3
January 1986. All 10 were in continuous sunlight after 1975, but in 2000
Cordelia re-entered the shadow of Uranus with each orbit, and by 2002 the
other 9 had followed suit.
The most recent discovery prior to this was Miranda by Gerard Kuiper in
1948, using the 82-inch McDonald Observatory reflector. It is the smallest of
the larger satellites, with a diameter of 293 miles, and orbits Uranus every
1.414 days at a distance of 80,405 miles. It is covered in grooves, and has
cliffs of ice 10 miles high. Miranda has been completely broken up into
separate lumps of rock and ice, and then re-formed from its components,
several times in its history. Initially, when re-formed, all the components
are scrambled, but as the interior heats up, the ice spreads to the surface,
while the rocks fall back to the centre. Saturn's moon Enceladus may have
undergone the same phenomena.
Ariel and Umbriel were discovered in 1851 by William Lassell (Umbriel had
previously been glimpsed by Herschel). Umbriel is fainter than Ariel but
slightly larger, 726 miles to Ariel's 719 miles, and takes 4.144 days to orbit
Ariel was imaged in detail by Voyager 2 over 35 per cent of its globe
in January 1986, and found to comprise a mixture of a rock core surrounded by
an ice mantle of water and ammonia. Parts of Ariel's surface are cratered,
though less than any other moons of Uranus, suggesting it is the youngest.
Each cratered section is separated by a series of ridges, which date from the
same period, and steep-sided troughs, or chasmata, run through both features.
The rest of the surface is made up of plains, with varying densities of
craters, suggesting the plains formed over a long period, and has evidence of
fluid volcanism. Some of the chasmata have become flooded by icy volcanic
flows to form the plains material. Ariel has an orbital period of 2.52 days.
The final two of the ten, Titania and Oberon were discovered by Herschel
himself in 1787, six years after his historic discovery of the planet. Titania
is the largest satellite, most strongly resembling Ariel, with a diameter of
981 miles and an orbital period of 8.706 days. Oberon, only marginally
smaller at 946 miles, but more heavily cratered, like Umbriel, is the furthest
away, with a mean distance from Uranus of 362,570 miles and a period of
revolution of 13.463 days. Its craters include Hamlet, Othello and Falstaff.
Uranus's 16th and 17th moons, S/1997 U1 and S/1997 U2
(preliminary designations), were discovered on 6/7 September 1997 using the
Hale Telescope sited on Palomar Mountain in California, the faintest to be
discovered from the ground. The discoverers were Brett Gladman of the
University of Toronto, Philip Nicholson and Joseph Burns of Cornell
University, and JJ Kavelaars of McMaster University. Both moons have eccentric
orbits, which are inclined to the equatorial plane, ranging from 2-5.5 million
miles from Uranus. All the other gas-giant planets have satellites of this
type, but none were previously known to exist around Uranus. Both are thought
to have been captured by Uranus's gravity from their orbit of the Sun, early
in solar system history, probably as comets. Both appear unusually red,
indicating an icy hydrocarbon surface that had been bombarded by energetic
The 18th moon, S/1986 U10, was found from a study of Voyager 2 images.
It is about 25 miles in diameter, and of icy composition. It is about 32,000
miles above the cloud-tops of Uranus. Its orbital and rotation periods are
both about 15 hour 18 minutes. The original discovery image was taken on 23
January 1986, and six other images were found to contain the new moon. A
hundred times nearer than the previous two, it has an orbit almost identical
to its neighbour Belinda, so that they pass one another once each month, the
first example of two objects in nearby orbits passing each other so slowly.
The discovery was made in 1999 by Erich Karkoschka from the University of
Arizona in Tucson, but as his find could not be confirmed by telescopes back on
Earth, two years later the International Astronomical Union decided to remove
it from its official list. Luckily, in 2003 observations made on August 25th using the Hubble Space Telescope's
Advanced Camera for Surveys, verified Karkoschka's claim. The 24th-magnitude object
was found about 48 degrees ahead of its predicted position.
The moons of Uranus are named after Shakespearian characters. Cordelia is
Lear's youngest daughter in King Lear. Ophelia is the fated heroine of Hamlet.
Bianca is the mistress of Cassio in Othello. Cressida is from Troilus and
Cressida. Desdemona is the heroine of Othello. Juliet was a star-crossed lover
in Romeo and Juliet. Portia dispensed justice in The Merchant of Venice.
Rosalind is the heroine of As You Like It. Puck was originally a malicious
spirit but in A Midsummer Night's Dream he was identified with Hobgoblin or
Robin Goodfellow. Miranda was the heroine of The Tempest. Ariel is the airy
spirit in The Tempest who employs magic and sings 'Full Fathom Five. In A
Midsummer Night's Dream Titania and Oberon are Queen and King of the Fairies.
The allusion to fairies suggests the innocent intuitiveness purported by
Uranus. The moons contain the implication that all of us bear the ability to
perform magic and intuitive functions if we can tap the innocence with which
we were born.
Last updated 29 November 2003