Everything you want to know about planet Uranus

here is everything you want to know about the planet Uranus.

William Herschel

“I have looked further into space than ever human being did before me. I have observed stars of which the light, it can be proved, must take two million years to reach the earth”

[Having identified Uranus (1781), the first planet discovered since antiquity.]
– William Herschel

In the darkness of space, an alluring planet was silently rolling in the vicinity of our star. Just waiting to be discovered, yearning to unveil its distinctive kind. Uranus.

History…

To the ancients, Uranus was a mystery. Many believed it to be nothing but a comet. Some also believed it to be a star somewhere far in space. They wanted to know about Uranus.

It was not until the late 18th century on 13th March 1781 that astronomer William Herschel discovered that the celestial body was actually a new world, a new member of the solar system family.

William Herschel - 40 foot telescope
William Herschel – 40 foot telescope

After the scientific community was sure about the celestial body is a planet the next question was, what to call it?

A name suggested by a German astronomer Johann Elert Bode was confirmed in the end.

The name was Caelus.

But wait! That doesn’t sound like U-R-A-N-U-S!

Wait a minute, I am getting there.

So this is the logic that Bode considered in order to name the newly discovered planet:-
Jupiter – means the father of Gods, Saturn – father of Jupiter and so the new planet should be the father of Saturn. And that’s Caelus in Roman.

According to the traditions, names from the ancient Roman religion must be used for the planets. But Bode, he decides to branch out a bit. He instead opted for the ancient Greek equivalent of Caelus, Ouranos, the Greek God of the heavens. The name was later Latinized to Uranus.

so now that you know about the history of Uranus, let us take a look look at the planets interesting characteristics.

Want to know more about Uranus…

Uranus is the 7th planet in the solar system. It takes 84 earth years for one revolution around the sun. Isn’t that the average life span of any human?

That means if we lived on Uranus, then we would experience all the 4 seasons just once and each lasting for about 20 years! I know you get bored wearing that raincoat for 2 months, now imagine wearing it for 20 years! Dreadful right?

When it was first observed and astronomers went for predicting its orbits, after some time they noticed that it was not following their predictions strictly. To this, they assumed that there must be a celestial body large enough to disturb the orbital path of Uranus.

Any guesses who it was? you are right, Neptune! But it wasn’t until 65 years later that it was discovered.

how far?

Uranus is located at a distance of 2.871 billion km from the sun. That’s 19.2 astronomical units from the sun or 19.2 times the distance of the earth from the sun. This distance differs greatly throughout its years.

aphelion and perihelion
aphelion and perihelion

At the aphelion (point in the orbit when the celestial body is furthest from its focus, in this case, the sun) the distance is 20.1 Au and at the perihelion (point in the orbit when the celestial body is the nearest to its focus, in this case, the sun) the distance is 18.3 Au. This creates a difference of 1.8 Au which is the biggest difference any planet has in its orbits aphelion and perihelion.

Due to this huge distance from the sun, the planet has the coldest temperature in the solar system, -370 degrees Fahrenheit or -223.3 degrees Celsius. The planet’s composition influences this greatly.

now that you know so much about planet Uranus, you can discuss it with your friends and colleagues. But I think you are still curious. continue reading to get to know more about Uranus.

But really how big is this planet?

In mass, it’s the least massive of all the gas giants.

To know how massive is Uranus, just imagine 14.5 earth mass molded to get one giant planet. Just for the comparison, Neptune comprises of 17 earth masses.

But you know one interesting thing about the diameter of Uranus? its greater than that of Neptune. Its 50,700 km wide (4 times that of the earth).

Because of the huge diameter and a small mass, the mass has to spread on a larger area which is why the gravity on Uranus (8.7 m/s) is just slightly lesser than on Earth (9.8 m/s).

Orientation…

orientation of planets
axis tilt of all the planet. 
image credit – NASA

If you go to see the rotation of all the planets, you’ll see that they appear to rotate like a top spinning on a surface. But in the case of Uranus its completely a different story.

Uranus has the weirdest orientation in the solar system. It has an axis tilt of 97.77 degrees. This means that the planet kind of rolls around its equator to make the revolutions.

This also means that unlike the poles of other planets that face upwards and downwards, the poles of Uranus will point towards and away from the sun. Interestingly this also has an effect on the orientation of Uranus’s 27 moons and its 13 rings.

The moons and rings of other planets in the solar system revolve around the home planet in a horizontal manner but in this case, it’s again different. The rings and moons of Uranus seem to have opted a divergent route. It revolves around the planet in a vertical fashion.

Just picture a giant wheel with the compartments being the moons and the rings and in the center lies the planet, Uranus.

This extreme orientation of the planet is theorized to be a result of a collision of the planet with an Earth-sized celestial body.

Composition…

Uranus composition
KelvinsongUranus diagramCC BY-SA 3.0

get to know what Uranus is made of…

Comprises of a rocky silicate material in the core that is smaller than the size of the earth.
The very next layer is made up of water, ammonia and methane ices (though referred to as ices, its 5000 degrees Celsius) which makes up its mantle.

So the mantle is just like a liquid ocean that surrounds the core.

The final layer is entirely the gas layer. And since it is gas, it takes a small amount of mass as compared to the mantle and the core. Takes just 0.5 Earth masses. This layer is comprised of hydrogen, helium and a 2.3 % of methane which gives it the beautiful cyan color.

Seasons…

get to know about the seasons on Uranus…

Since the planet rolls around the equator, it experiences seasons, unlike any other planet.

During Equinox (the time when the sun crosses the celestial equator) the planet has a normal day and night cycle.

But,

During solstice (the time of the year when the sun is highest or lowest in the sky) one side of the planet faces away from the sun and the other side faces towards the sun the entire time.

Uranus

Also when the planet approaches the solstice, the poles of the planet seem to brighten and a collar like formation can be seen at the poles. When the planet recedes away, the collar slowly dims. It is been theorized that this happens due to the thickening of methane clouds. But the real reason for the cloud formation is still a mystery.

And if you wonder what must be happening at the equator, only a very small part or strip near the equator experiences a crazy phenomenon. The sun rises from the horizon for a short period of time and sets on the same horizon.

That’s crazy!

Due to the crazy orientation of the planet, it experiences 42 years of daylight and 42 years of darkness.

And just like its Axis tilt, the rotation speed also leaves no chance in surprising us. Uranus rotates so fast that it takes just 17 hours and 14 minutes to complete one rotation. Imagine living there and having a test the next day, you don’t have 24 hours anymore, better speed up!

And that’s just the rotation speed of the planet as a whole. You remember right? it came to notice that some parts of the planet rotate faster than the others this was because the planet didn’t have a solid surface. These parts can make a complete rotation in just 14 hours. Strong winds greatly influence the speed.

Storms on this planet are relatively less as compared to that on other gas giants. The seasonal changes are thought to be responsible for these storms.

Diamonds?

High-pressure experiments suggest a large number of diamonds are formed from methane on the ice giant Uranus. The same goes for Neptune. These diamonds, rain through the mantle like hailstones.

It is also believed that the base of the mantle can be a layer of liquid diamonds with solid diamonds floating in it.

Just picture the icebergs in the Antarctic’s, only here it isn’t water but pure liquid diamonds!

Rings…

Coming to that exclusive feature of gas giants.

Uranus has 13 young rings. Young because the rings are found to be just 600 million years old, much after Uranus’s birth year.

Discovering the rings…

The rings were discovered in 1977.

But how did they discover such a faint and dark ring system?

When an occultation of star occurred (an astronomical event that occurs when one celestial object is hidden by another celestial object that passes between it and the observer when the nearer object appears larger and completely hides the more distant object) the star dimmed a few times on either sides of Uranus as Uranus moved in front of it. This confirmed the presence of a ring system that obstructed the light of the star, dimming it a few times.

Although huge in diameter, these rings are just a few km wide and are made up of extremely small particles. The biggest particle range only a few meters across.

These particles are mainly made up of water ice and dark radiation processed organics. Believed to be the result of high impact collision of some of the moons in the past.

Visit…

Uranus has seen only one visit and that was from the Voyager 2 in 1986.

When Voyager 2 flew past Uranus it discovered a lot of its moons and even provided some close-up images of the planet. But it had only discovered 11 rings.

Then came the Hubble telescope. It discovered 2 additional rings that were never seen before. Interestingly, the newly discovered outer most ring appeared to be twice as large as the previously thought outer most ring.

Moons…

Uranus has a total of 27 moons that are divided into 3 categories

Uranus rings and moons
Ruslik0Uranian rings scheme, marked as public domain, more details on Wikimedia Commons


Inner moons…

The names of these moons in order of increasing distance from Uranus:-

These are 13 moons that lay close to the rings and are thought to have provided the rings its material by collisions in the past.

Puck.

The largest among these inner moons is Puck, with a diameter of 162 km.

Major moons…

The next group consists of 5 major moons.

Names in the order of increasing distance:-

Titania is the largest moon of Uranus and the 8th largest moon in the solar system with a diameter of 1,576.8 km.

All the major moons are a mixture of water and rock materials with an exception of one moon, this moon is Miranda as it comprises mostly of water ice.

The core is made up of rocky material and the mantle is made up of ice. But there lies another layer in between the core and the mantle that is nothing but an ocean of liquid water.

Interesting fact! The major moons of Uranus show a similar orientation to that of its home planet.

Irregular moons…

Names in the order of increasing distance:-

  1. Francisco
  2. Caliban
  3. Stephano
  4. Trinculo
  5. Sycorax
  6. Margaret
  7. Prospero
  8. Setebos
  9. Ferdinand

These 9 moons are the last in the list and likewise, lay at the outer ends just after the last major moon Oberon.

These are captured objects. The smallest being 20 km wide (Trinculo) and the largest being 200 km wide (Sycorax).

One irregular moon named Margaret is the only known irregular prograde moon of Uranus and holds the record of “the most eccentric orbit of any moon” in the solar system.

Magnetosphere…

In 1986, when Voyager 2 first flew by Uranus, it revealed something pretty amazing. The magnetosphere of Uranus seemed to have a tilt of 60 degrees! To compare this, the earth’s magnetic field has a tilt of 11 degrees due to which we stay protected from the solar flares as our magnetic field remains stable.

But the magnetic field of Uranus is constantly in motion due to which the magnetic fields on the planet get so unstable that the temperature gets exposed to the solar winds.

An even crazier thing about the magnetosphere is that for any given planet if we see, the magnetosphere usually originates from the geometric center.

but not here.

It is 59 degrees off with respect to the rotation axis. this means that the magnetic field at the north pole will be stronger as compared to the south pole.

There are two theories that explain why. One says that the liquid diamond ocean deflects the magnetic field and the other theory is that it’s not the core that produces the magnetic field but rather it’s the water mantle. But both the theories remain unproven and the real reason for this weird magnetosphere is still a mystery.

The magnetic field of planet Uranus is as strong as that of the Earth. And because of its highly unusual offset with respect to the rotational axis, the magnetosphere rotates so wildly that it produces a magnetotail that extends millions of km into space.

conclusion…

7th planet in the solar system.

Located at a distance of 2.871 billion km from the sun.

Least massive of all the gas giants.

Has the most extreme orientation of 97.77 degrees.

Experiences 42 years of daylight and 42 years of darkness.

Has a total of 27 known moons and 13 rings.

What is your theory regarding the crazy tilt in the magnetosphere?

sahil asolkar

Sahil Asolkar

writer and co-founder

Sahil Asolkar is a writer, poet, and shows a good interest in astronomy. His work can be seen in the articles he writes for Astronomiac.

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