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Essay On The Planet Uranus Is Called

  • Uranus cannot be seen from the Earth without a telescope.

       

  • The seventh planet from the Sun, it was not known in ancient times, unlike the planets from Mercury to Saturn.

       

  • Uranus was first seen by William Herschel in 1781 during a survey of the sky using a telescope.  In 1782 George III appointed Herschel as Astronomer Royal.

       

  • William Herschel was born in Hanover, Germany.  He moved to England in 1757 in order to follow a career as a musician but after buying a book on astronomy he became interested only in watching the sky.

       

  • Herschel also discovered 2 of Uranus’ moons with a larger telescope.

       

  • Uranus has a total of 27 moons, most of whom are named after characters in Shakespeare’s Midsummer Night’s Dream.  The five major moons are called  Titania, Oberon, Miranda, Ariel and Umbriel.  Umbriel is not from Shakespeare but is the “melancholy sprite” in a poem by Alexander Pope.

 

Figure 1: Uranus and its moon Ariel, the white dot, and Ariel’s shadow.

  • Uranus is one of the “gas giants”, the four outer planets which are entirely composed of gas, Jupiter, Saturn, Uranus and Neptune.

       

  • Most of the centre of Uranus is a frozen mass of ammonia and methane, which gives it the blue-green colour.  The atmosphere also contains hydrogen and helium.

       

  • Uranus orbits the Sun lying on its side and takes 84 years to complete one orbit.  The Earth goes round the Sun in 365 days, one year.

       

  • Because Uranus is lying on its side as it orbits the sun, for nearly a quarter of its orbit one pole of the planet is in complete darkness.

       

  • Uranus takes 17.9 hours to turn once on its own axis, faster than the Earth, which takes 24 hours and gives us the change from day to night.

       

  • Uranus was the ancient Greek God of the heavens whose sons were the Giants and Titans.

       

  • Uranus is the smallest of the four “giants”, but is still several times larger than the Earth.  It has a diameter of 29297 miles, or 47, 150 kilometres, compared to the Earth’s diameter of just under 8000 miles, or 12,760 kilometres.

       

  • Uranus is 1782 million miles, or 2869 million kilometres from the Sun.  Figure 1 does not show the distances from the Sun to scale, but Figure 2 lets you have an idea of how much further Uranus is from the Sun than the Earth.

       

  • Distances in the Solar system are measured in Astronomical Units (AU), with the Earth’s distance from the Sun being 1 AU.  Uranus is 19.2 AU from the Sun.  Figure 2 shows the distances of the first seven planets from the Sun, measured in AU.
  • In 1977 Uranus passed in front of a star and astronomers observing the planet through giant telescopes saw nine rings around the planet.  These are very faint and not easily seen, unlike the rings around Saturn.

       

  • Photographs sent back by the Voyager spacecraft in the 1980s showed a further two rings round the planet.

       

  • The Hubble Space telescope found two more very faint rings, very distant from the planet, between 2003 and 2005, so we now know of a total of 13 rings.

       

  • Scientists do not yet understand exactly what causes these rings or exactly what they consist of.

       

  • From the time when Uranus was first observed scientists noticed that at certain points in Uranus’ orbit the planet was being pulled further out into space.

       

  • In the 19th century certain astronomers worked out that this must be because of the pull of gravity from another planet beyond Uranus.

       

  • By making mathematical calculations based on the observations of Uranus, two astronomers, Adams and Le Verrier, identified where this other planet must be.

       

  • The planet which was exerting a gravitational pull on Uranus was Neptune, 10.9 AU further out into space.

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Nineplanets, by Bill Arnett

Welcome to the Planets

Alternate Images of Uranus

Uranus is the seventh planet from the sun and the first to be discovered by scientists. Although Uranus is visible to the naked eye, it was long mistaken as a star because of the planet's dimness and slow orbit. The planet is also notable for its dramatic tilt, which causes its axis to point nearly directly at the sun.

British astronomer William Herschel discovered Uranus accidentally on March 13, 1781, with his telescope while surveying all stars down to those about 10 times dimmer than can be seen by the naked eye. One "star" seemed different, and within a year Uranus was shown to follow a planetary orbit.

Uranus was named after the Greek sky deity Ouranos, the earliest of the lords of the heavens. It is the only planet to be named after a Greek god rather than a Roman one. Before the name was settled on, many names had been proposed for the new planet, including Hypercronius ("above Saturn"), Minerva (the Roman goddess of wisdom), and Herschel, after its discoverer. To flatter King George III of England, Herschel himself offered Georgium Sidus ("The Georgian Planet") as a name, but that idea was unpopular outside of England and George's native Hanover. German astronomer Johann Bode, who detailed Uranus' orbit, gave the planet its ultimate name. Bode argued that as Saturn was the father of Jupiter, the new planet should be named for the father of Saturn. Bode's colleague, Martin Klaproth, supported his choice and named his newly discovered element "uranium." [Related: How Do You Pronounce 'Uranus'?]

Perturbations in Uranus' orbit ultimately helped astronomers precisely locate Neptune in the mid-19th century.

Physical characteristics

Uranus is blue-green in color, the result of methane in its mostly hydrogen-helium atmosphere. The planet is often dubbed an ice giant, since 80 percent or more of its mass is made up of a fluid mix of water, methane, and ammonia ices.

Unlike the other planets of the solar system, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star. This unusual orientation might be due to a collision with a planet-size body, or several small bodies, soon after it was formed.

This unusual tilt gives rise to extreme seasons roughly 20 years long, meaning that for nearly a quarter of the Uranian year, equal to 84 Earth-years, the sun shines directly over each pole, leaving the other half of the planet to experience a long, dark, cold winter.

Uranus has the coldest atmosphere of any of the planets in the solar system, even though it is not the most distant from the sun. That's because Uranus has little to no internal heat to supplement the heat of the sun.

The magnetic poles of most planets are typically lined up with the axis along which it rotates, but Uranus' magnetic field is tilted, with its magnetic axis tipped over nearly 60 degrees from the planet's axis of rotation. According to Norman F. Ness, et al., in an article in the journal Science in 1986, this leads to a strangely lopsided magnetic field for Uranus, with the strength of the field at the northern hemisphere's surface being up to more than 10 times that of the strength at the southern hemisphere's surface, affecting the formation of the auroras. A 2017 study suggested the lopsided nature of Uranus' magnetic field may also lead it to flicker on and off every time the planet rotates (about every 17.24 hours).

Orbital characteristics

Uranus' parameters, according to NASA:

Average distance from the sun: 1,783,939,400 miles (2,870,972,200 kilometers). By comparison: 19.191 times that of Earth

Perihelion (closest approach to the sun): 1,699,800,000 miles (2,735,560,000 km). By comparison: 18.60 times that of Earth

Aphelion (farthest distance from sun): 1,868,080,000 miles (3,006,390,000 km). By comparison: 19.76 times that of Earth

Composition & structure

Atmospheric composition (by volume): 82.5 percent hydrogen, 15.2 percent helium, 2.3 percent methane

Magnetic field: Magnetic pole tilt compared to rotational axis: 58.6 degrees

Composition: About 80 percent of the composition of Uranus is, by mass, thought to be made up of a hot dense fluid of icy materials — water, methane and ammonia — above a small rocky core.

Internal structure: Mantle of water, ammonia and methane ices; core of iron and magnesium-silicate

Orbit & rotation

Axial tilt: 97.77 degrees, compared to Earth's 23.5 degrees

Seasonal cycle & length: Approximately 21 years per season

Orbital period: Approximately 84 Earth years

Uranus' climate

The extreme axial tilt Uranus experiences can give rise to unusual weather. As sunlight reaches some areas for the first time in years, it heats up the atmosphere, triggering gigantic springtime storms roughly the size of North America, according to NASA.

Ironically, when Voyager 2 first imaged Uranus in 1986 at the height of summer in its south, it saw a bland-looking sphere with only about 10 or so visible clouds, leading to it to be dubbed "the most boring planet," writes astronomer Heidi Hammel in "The Ice Giant Systems of Uranus and Neptune," a chapter in "Solar System Update" (Springer, 2007). It took decades later, when advanced telescopes such as Hubble came into play and the seasons changed, to see extreme weather on Uranus, where fast-moving winds can reach speeds of up to 560 miles (900 kilometers) per hour.

In 2014, astronomers got their first glimpse at summer storms raging on Uranus. Strangely, these massive storms took place seven years after the planet reached its closest approach to the sun, and it remains a mystery why the giant storms were so late.

Other unusual weather on Uranus includes diamond rain, which is thought to fall thousands of miles below the surfaces of icy giant planets such as Uranus and Neptune. Carbon and hydrogen are thought to compress under extreme heat and pressure deep in the atmospheres of these planets to form diamonds, which are then thought to sink downward, eventually settling around the cores of those worlds.

The rings of Uranus

The rings of Uranus were the first to be seen after Saturn's. They were a significant discovery, because it helped astronomers understand that rings are a common feature of planets, not merely a peculiarity of Saturn.

Uranus possesses two sets of rings. The inner system of rings consists mostly of narrow, dark rings, while an outer system of two more-distant rings, discovered by the Hubble Space Telescope, are brightly colored, one red, one blue. Scientists have now identified 13 known rings around Uranus.

A 2016 study suggested the rings of Uranus, Saturn and Neptune may be the remnants of Pluto-like dwarf planets that strayed too close to the giant worlds long ago.

Uranus' moons

Uranus has 27 known moons. Instead of being named after figures from Greek or Roman mythology, its first four moons were named after magical spirits in English literature, such as William Shakespeare's "A Midsummer Night's Dream" and Alexander Pope's "The Rape of the Lock." Since then, astronomers have continued this tradition, drawing names for the moons from the works of Shakespeare or Pope.

Oberon and Titania are the largest Uranian moons, and were the first to be discovered, by Herschel in 1787. William Lassell, who was the first to see a moon orbiting Neptune, discovered the next two, Ariel and Umbriel. Then nearly a century passed before Miranda was found in 1948.

Then, Voyager 2 visited the Uranian system in 1986 and found an additional 10, all just 16 to 96 miles (26-154 km) in diameter — Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida and Belinda — and each roughly made half of water ice and half of rock. Since then, astronomers using the Hubble Space Telescope and ground-based observatories have raised the total to 27 known moons, and spotting these was tricky — they are as little as 8 to 10 miles (12 to 16 km) across, blacker than asphalt, and nearly 3 billion miles (4.8 billion km) away.

Between Cordelia, Ophelia and Miranda is a swarm of eight small satellites crowded together so tightly that astronomers don't yet understand how the little moons have managed to avoid crashing into each other. Anomalies in Uranus' rings lead scientists suspect there might still be more moons, closer to Uranus than any known.

In addition to moons, Uranus may also have a collection of Trojan asteroids — objects that share the same orbit as the planet — in a special region known as a Lagrange point. The first was discovered in 2013, despite claims that the planet's Langrange point would be too unstable to host such bodies.

Research & exploration

NASA's Voyager 2 was the first and as yet only spacecraft to visit Uranus. It discovered 10 previously unknown moons, and investigated its unusually tilted magnetic field.

In 2011, the Planetary Science Decadal Survey recommended NASA consider a mission to the icy planet. In 2017, NASA suggested a number of potential future missions to Uranus in support of the forthcoming Planetary Science Decadal Survey, including flybys, orbiters and even a spacecraft to dive into Uranus' atmosphere.

Additional resources

Learn more about Uranus:

Learn more about the solar system:

Additional reporting by Nola Taylor Redd, Space.com Contributor

The butt of solar system jokes, Uranus is also a spectacular blue planet still hiding many scientific secrets. See how much you know:

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