I think the alliteration of Uranus & Unique fits perfectly, and this post will explain why.
In this post, we’ll be talking about Uranus’ rings, it’s light blue colour, its gorgeous moons, and its downright stupid naming!
Let’s start off with what kind of planet Uranus is, and that is an ice giant. This will layout the foundation for this post, and will explain a lot!
Similarly to Jupiter & Saturn, Uranus is a giant planet with a relatively small core and a huge atmosphere. It should have a mantle made of fluid (that’s liquid and/or gas) and a mainly hydrogen & helium atmosphere. It sounds like Uranus would be a bog-standard gas giant, right?
The main difference is that Uranus is an ice giant, and ice doesn’t necessarily mean water ice in the astronomy field. I mean it’s made of volatile substances such as ammonia, methane, and of course, water. These chemicals will very quickly evaporate/sublimate into vapors and gases, and have low freezing points, with Methane or example freezing at -182 degrees C! The mantle is mainly made of these 3 ices, plus Hydrogen & Helium.
In addition to temperature, pressure can also play a big part in whether a chemical is solid, liquid, or gas, or if it even has a liquid stage at all. It’s expected that Uranus’ mantle is a mix of liquid & gas, but no precise measurements of the mantle have been made yet to confirm this idea.
Contrary to what you might think, both pressure and temperature in Uranus are extremely high, despite being so far away from the Sun where the surrounding temperature is close to absolute zero with almost no pressure! Even some parts of Uranus’ atmosphere reach 800 Kelvin.
With the pressure and temperature being so high in the planet, the conditions might be perfect for breaking up methane (CH4) into carbon and hydrogen and forming diamonds with the carbon under the high pressure. Thus, it could be possible to have diamond hail in Uranus’ mantle and lower atmosphere. Now I think that is pretty unique!
Uranus’ Blue Atmosphere
Now let’s talk about the atmosphere. The majority of our information on Uranus is on the atmosphere, mainly because it’s the easiest to see with a telescope.
We can actually split the atmosphere into a troposphere, stratosphere, and thermosphere & ionosphere in order of increasing altitude.
It’s in the stratosphere and thermosphere where you get a spike in temperature as you increase in altitude i.e. as you move further from Uranus, it gets hotter. That sounds completely contradictory, but this happens because of the methane & hydrocarbons (that’s chemicals made of just hydrogen and carbon, hence the name) mixed in the atmosphere being radiated by rays from the sun and releasing a lot of heat. This makes sense since methane is a greenhouse gas, and hydrocarbons are fossil fuels (expect they didn’t come from Uranian fossils, they were just there).
The temperature in these atmosphere layers increases from 50K to 800K, which is a huge amount either too cold or too hot for Earthly life to survive!
Methane has another trick up its sleeve! Uranus itself is only a couple percent composed of methane, but methane has characteristic blue absorption and emission bands. This means the interaction with the suns rays with methane is what makes the planet blue, ad there is just enough methane spread out in the atmosphere to add a slight blue tint to the planet!
Its Beautiful….ly Dim Rings and Odd Tilt
A lot of people know that Uranus points towards the Sun, but nobody yet knows how exactly this tilt happened. Uranus’ tilt is 97.7 degrees, which means that for the 84 Earth year orbit it takes for Uranus, most of the planet spends 42 years in the sun, then 42 years in darkness. There is a tiny strip around the equator that instead has it the opposite way, with rapid changes from day to night.
Why did this tilt happen? Most astronomers agree that it almost certainly isn’t naturally made. When planets are forming, they’re made from a protoplanetary disk around a young star. This disk starts off spinning, so when planets form they will conserve angular momentum and spin along the same axis. We see this with Mercury, which is almost completely untilted. What might have happened is a huge collision, where some object a bit bigger than Earth could have knocked Uranus on its side. This could also explain Venus 180 degree tilt too.
Tilted with the planet are Uranus’ rings. These likely didn’t form with the planet, but a bit later, and the structure is split into 13 dusty and dim rings. From the closest moving outwards, we have 1986U2R/ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν and μ. No, that’s not the Greek alphabet, astronomers are just terrible at names.
I know spacecraft pictures make the rings look lovely and bright, but these rings are very hard to see. They’re likely made of mostly dimly lit dust with very little ice, which is quite ironic since Uranus is an ice giant.
Intermingled in these rings are 27 Uranian moons, with mostly Shakespearean names.
Titania is the largest moon of Uranus, but only 8th largest in the solar system. The only reason I mention Titania is because of the names of its craters. My favourites are Jessica & Gertrude.
My favourite Moon is Miranda, mainly because of the surface. It has surface features that likely were caused by tectonic activity in the past, such as coronae, scarps, graben, and of course craters. This is a truly mesmerizing moon!
It’s Funky Name and The 70 Years Before It.
The current name, Uranus, is named based on Cronus, the Greek equivalent of Saturn. It took 70 years after Caroline & William Herschel’s discovery of the planet for a name, with William deciding to name it…the planet…Georgium Sidus. That is Latin for George’s Star. I am not joking.
In 1782 Johan Bode proposed the name Ouranos, in order for the planet to fit in with the other planet’s names and also to complement Saturn. This name, also following the naming of the element Uranium, caught on and thankfully cemented itself as the name for the 7th planet from the Sun.
Thanks. Good update. Nice to have you back
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Thank you Clive! I am alive, and now work is lessening I will be posting more.
NASA announced they want to launch a mission to Uranus in the 2030’s, which would probably get there in the 2040’s. I’m both super excited for that mission and I’m also dreading it, due to the numerous dumb jokes the mission will inspire.
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Finally! It feels like Uranus is the least loved planet by space agencies, and it’s not fair! I would have hoped as a civilization we would move on from Uranus jokes, but alas that will definitely not be the case!
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Before the announcement, I read somewhere that a Uranus mission and a Neptune mission were in close competition, and I thought for sure Neptune would win out.
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