Jupiter.
King of the Roman Gods.
Fitting, then, that it should be the namesake of our solar system's largest planet.
Not only is Jupiter the largest planet (11 times bigger than the Earth), it is also the heaviest. Jupiter alone has more that 2.5 times the mass than ALL the other planets in the solar system combined. This is especially impressive when you consider that Jupiter is a gas planet, being made up almost entirely of gases like hydrogen, some helium, and trace amounts of methane and ammonia.
But that's not what makes Jupiter so intriguing.
Listed below are what does.
1. Clouds and Storms
Unsurprisingly for a gas planet, Jupiter has a stupendous atmosphere. And since the gigantic planet spins so dizzyingly fast (it completes one rotation or day in just 9.5 hours, compared to 24 hours for the much smaller Earth), that atmosphere gets thrown around and results in magnificent clouds and storms.
Literally every inch of Jupiter is completely enveloped by massive clouds and storm systems. Looking at pictures of Jupiter, the delectable strips, swirls, and patterns visible on it's surface are all clouds and violent storms.
The dark bands or stripes along the top and bottom of its surface are perpetual clouds that circle the entire planet.
These stripes are easily visible via a telescope, as seen in the picture below taken by iPhone hooked up to my telescope.
<pic>
Arguably its most recognisable feature is the Great Red Spot, a massive cyclone which has been raging for at least 350 years and has wind speeds of 430 to 640 km/h.
It is larger in size than the entire Earth!
Its wind speed may seem like a lot. Until you consider that elsewhere on Jupiter, wind speeds reach 1,400 km/h! For comparison, top wind speeds in Earth's most violent storms (occurring just once every few decades) reach just 250 km/h.
To call it a tumultuous atmosphere would be quite the understatement.
2. An Even More Extreme Interior
As extreme as it is, Jupiter's atmosphere barely scratches the surface (literally!).
If you were to fall into Jupiter (wearing a hypothetical, indestructible suit), you would first get thrown around by the nightmare winds worse than a fly gets thrown around in a hurricane.
Soon enough, rain and hail would join the scene, except most of it would be made up of liquid ammonia.
Along the way, you'd probably be struck by at least a few of the millions of lightening bolts that are a perpetual occurrence in Jupiter's upper atmosphere. Extra unhelpful is the fact that lightening on Jupiter is thousands of times more powerful than that on Earth.
While you're contemplating if this adventure was a good idea, the skies would get darker as you fell deeper and the clouds obscure the sunlight. Shortly thereafter, you'd fall deep enough so that all sunlight would be blocked and it would become completely pitch dark
The atmosphere would have ended. But there is no solid ground on Jupiter because remember, it's entirely a gas planet. So now, you'd still be suspended in a hydrogen and helium environment, but Jupiter's crushing gravity would have compressed said gases to the density of liquids.
It would still be completely dark, with occasional illumination from the lightening of the atmosphere above.
Hope you're enjoying swimming in this liquid soup, because this soup ('ocean' is probably a better word) extends to a depth of some 20,000 kilometers (for comparison the deepest point in Earth's oceans is only 11 kilometres deep).
Your adventure would hit its high note when you finally pass through the entire liquid layer and fall so deep into Jupiter, that you'd reach a truly bizarre place (as if you hadn't experienced that so far!). At these extreme depths, hydrogen gas would be compressed by the extreme gravity to the density of a solid. Except, the same pressure would result in an extremely high temperature which would keep the hydrogen fluid. Thus resulting in an exotic state called 'liquid metallic hydrogen'.
So there you'd be...in a massive ocean of hydrogen gas, squeezed to the density of a solid, but hot enough to behave like a liquid, that conducts electricity (like a metal, hence the term 'metallic')!!
And you'd be floating on top of an ocean of this, 'stuff', that'd be a whole 40,000 kilometres deep.
Enough time for you to ponder, given the state of things...is it really accurate to call Jupiter a 'gas' planet?
3. Hottest Place in the Solar System
Quick! What's the first thing that comes to mind when I ask you to guess the hottest place in the solar system?
'The Sun' would be a pretty good and frankly unanimous guess.
Would it surprise you, then, to learn that that's the wrong answer??
No, it's not a trick question. Not even the centre of the Sun is the right answer.
In fact, the hottest place in the solar system is a region just outside of Jupiter's atmosphere, in space, within Jupiter's magnetosphere (or the region of space under the influence of Jupiter's magnetic field).
Due to the aforementioned ocean of liquid metallic hydrogen, Jupiter has the strongest magnetic field of all planets within the solar system.
This extreme magnetic field results in extreme energy, heating up any matter within the region to an unimaginable 200 Million degree Celsius!
By comparison, the surface of the Sun is a just 5,500 degrees Celsius. Even the centre of the Sun is no match, for it maxes out at 15 Million degrees Celsius.
Thus, as counter intuitive and incredulous as it may sound, the space surrounding Jupiter is 13 times hotter than the centre of the Sun! Despite the latter being a gargantuan nuclear fusion furnace thousands of times larger than Jupiter itself.
Of course, there is a caveat.
This temperature only applies to plasma, or ionic gas.
Now the density of this plasma is very low, which would significant thermal transfer. Meaning, that any solid object in that region would not be heated to 200 Million degrees (though it would still get EXTREMELY hot).
But since plasma here does heat up to 200 Million degrees Celsius, and since plasma IS a state of matter which in fact makes up 99.9% of the Sun's mass, thus Jupiter's magnetosphere is legitimately hotter than the surface of the Sun.
<Hottest place in the solar system, seen in real time through my telescope>
4. In the Neighborhood of Alien Life?
Last, but certainly not the least.
Science fiction and even general astrophysics almost exclusively imagines alien life to originate from beyond the solar system.
This is not unreasonable, given how extreme and unfriendly to life conditions are on every single body outside the Earth.
Thus, science fiction authors imagine (and astrophysicists posit) alien life to exist on planets with earthlike conditions in other parts of our galaxy or even in other galaxies (though whether life has emerged on such planets is obviously unknown).
It is virtually certain that no biological life (however exotic) could exist on any heavenly body (i.e. planets, moons, asteroids, comets, or other) within our solar system.
Not on it (as in, on the surface).
But what about...in it??
The mighty Jupiter has 80 moons (that we know of so far, there may be more that we haven't detected yet).
Its 4 largest moons are the so-called 'Galilean moons', named so since they were discovered by the Italian astronomer Galileo Galilei in 1610 AD.
These moons are almost as large as planets, and can be seen easily through a standard telescope, as seen in the picture below take by my iPhone through my telescope.
<pic telescope>
Of these 4 moons, at least three i.e. Ganymede, Europa, and Callisto are known to have large oceans of liquid water. And the same is true for Saturn's moon of Titan and Enceladus.
Not ON their surface, obviously, since they are so far from the Sun and hence far below the threshold of ice formation. In fact their surfaces are solid frozen ice with temperatures of -160 to -200 degree Celsius.
But some 15 to 25 kilometres below the surface layer of ice, temperatures are warm enough so that there exist massive oceans of liquid water.
Enormous in size, these oceans make the oceans of Earth resemble a thin puddle by comparison. For they are estimated to be between 40 to 150 kilometres deep (compared to the deepest point of the Earth's oceans being just 11 kilometres deep).
It goes without saying that the existence of liquid water presents a serious and major possibility for the existence of biological life. And because life exists even in the deepest points of Earth's oceans (despite the frigid temperatures, complete absence of sunlight, and crushing pressures), it is reasonable to think that the same could be true in the oceans of Jovian and Saturnian moons.
We are currently aware of over 300 species of animal life living at the bottom of the Earth's oceans. Despite extreme pressures, absence of light, and sub-freezing temperatures, these organisms survive off the heat energy released by hydrothermal vents (which are fissures on the ocean floor that discharge water heated by geothermal activity).
The Jovian and Saturnian moon mentioned above too experience significant geothermal activity since they are 'squeezed' by Jupiter and Saturn's overpowering gravity, resulting in a phenomenon called 'tidal heating'. Plus, there's moons' have been detected to have hydrocarbons that support the complex chemical reactions forming the basis of biological life. So on paper, Europa contains all the ingredients needed to support life within its oceans.
This leads to a startling realisation: It is very possible that alien life might exist right here in our solar system, in places which we can see in real time just with a telescope from our backyards.
<telescope pic. You're looking at a real image of a place where alien life possibly exists...here!>
Notes:
1. NASA's upcoming Europa Clipper mission plans to launch a spacecraft in 2024 with the express purpose of investigating Europa and its ocean in much greater detail. Specifically to analyse whether life could exist within its ocean. See https://europa.nasa.gov/
2. Although unfortunately the spacecraft will not be landing on Europa and instead will only be orbiting it and taking measurements, there are plans for future missions in which a 'lander' would land on the Europa (see https://en.wikipedia.org/wiki/Europa_Lander) and then deploy a 'cryobot' or a robotic submarine which would use nuclear power to generate enough heat to melt its way through the ice surface and into the ocean below to explore what wonders (if any) lie there.
Appendix A: How Do We Know These Things?
i) Jupiter's Composition: We know that Jupiter is made up of hydrogen (and a tiny bit of helium, aethane, ammonia, and trace amounts of other elements) thanks to a technique called mass spectroscopy. Long story short, it involves analysing the light reflected off the atmosphere at a spectral level. Just like every object 'looks' slightly different because the light reflected off it is slightly different, similarly if we closely analyse that light at the level of its wavelengths, we can determine exactly what elements (or molecules) the object is made up of, because the spectral signature of each element or compound is unique...somewhat like a fingerprint.
ii) Jupiter's Storm Speeds: Seen visually (even through telescopes), Jupiter's clouds may appear still. But when observations are taken over days or weeks, tony movements can be discerned. Averaged over the duration of observation and the size of said clouds, exact speeds can be calculated. Thanks to the Hubble Space Telescope and Juno orbiter, much closer pictures were possible which resulted in very accurate estimates with tiny probabilities of error.
iii) Jupiter's Interior: Jupiter's interior is of course, entirely invisible, even via the most powerful telescopes that rely on visual or electromagnetic radiation. But since Jupiter's composition is known, its interior can be discerned by calculating the effect of gravity on the overall extrapolated mass per its size. The same technique is used to quite accurately discern the composition of the Earth's mantle and core. Any errors in calculation can be sorted by comparing the theoretical gravitational results against the planet's astronautical movement about the Sun, said movement being dependably calculable and confirmable via a multitude of observational instruments.
iv) Jupiter's Magnetosphere: Jupiter's magnetosphere was theorised based on its size and composition early on. Once the Voyager 1 and Voyager 2 space probes passed by Jupiter, experimental readings were taken, and these were later verified to a great degree by the Juno spaceprobe.
v) Europa and Titan's Oceans: Europa's composition was discerned by mass spectograpy and gravity physics as explained above. Thereafter, it was discovered by Juno that both Europa and Titan exude aurorae similar to the ones one the Earth's poles. Whilst aurorae themselves are simply a result of an astronomical body's ionosphere or magnetosphere's effect on solar radiation, the detailed physical analysis of the aurorae strongly alludes to the presence of a large body of liquid water within both of said moons.
Appendix B: Jupiter's Inhabitants Imagined
One of my favourite science fiction stories of all time is Victory Unintentional by Isaac Asimov. It tells of a trio of robots sent by humans into Jupiter, and their encounter with the puzzlingly antagonistic Jovians (i.e. fictional alien inhabitants of Jupiter). A short and humerous story that relates quite well to the topics of this post. I encourage you to read it, it starts on page 4 of this page.
References:
work in progress
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