#190 What is the core of Jupiter like?

I learned this today. Nobody actually knows what the core of Jupiter is like. The most predominant theory is that it has a rocky core surrounded by a layer of metallic hydrogen.

Jupiter is the largest planet in the solar system. It is 1,321 the volume of Earth and is a gas giant. It is often known as a failed sun because it has all of the properties of a sun, except it doesn’t have enough mass for nuclear fusion to begin. Hydrogen can be converted into helium if there is enough pressure. Jupiter is made of exactly the same materials as the sun, but it is only 0.1% the size of the sun. That gives an idea of just how massive the sun is. Jupiter would need to be about 80 times larger to have a gravity high enough to generate the pressure and temperature needed to start nuclear fusion.

There are several theories of how Jupiter formed. One of them is that Jupiter started to form much farther out from the sun to where it is now. It was formed by several rocky and icy proto-planets smashing into each other. As its gravity increased, it grew larger. It is thought to be the first planet that formed in the solar system. The theory then is that as it got larger, the sun’s gravity pulled it closer, reducing its orbit. There, it caused two giant proto-Earths to collide and destruct. Jupiter was then pulled away from the sun by its interaction with Saturn’s gravity to end up where it is now. The detritus from the destroyed super-Earths formed into all of the planets in the inner solar system. Once Jupiter had retreated, it began to hoover up the dust and gas that was orbiting the sun. As it grew larger, its gravity increased, and it hoovered up more and more material until it reached its current size.

It is possible that Jupiter could have formed from simply a ball of gas, and then when its mass grew large enough, it collapsed in on itself and made a metallic hydrogen core. However, that is less likely than gas forming around a rock and ice solid core.

This is the reason why many people think that Jupiter has a solid core. This and the results of the Juno space probe.

From Earth, it is impossible to see inside Jupiter’s atmosphere because it is too thick. The only space probe that has been into Jupiter’s atmosphere was the Galileo space probe. After orbiting the planet for 14 years taking many invaluable observations, the space probe was destroyed in the atmosphere of Jupiter. The probe only managed to get 200km into the atmosphere before it was crushed by the immense pressure and NASA lost contact with it.

The atmosphere of Jupiter starts with about 50 km of clouds followed by 21,000km of hydrogen and helium in a gas state. Towards the bottom of this layer the gas turns to a liquid because of the pressure. Underneath the liquid hydrogen, there is a 40,000km deep layer of liquid metallic hydrogen. The temperature under all of this weight is about 30,000℃, which is not enough to start nuclear fusion.

The theory is that underneath this layer of liquid metallic hydrogen is a solid core. Now, what this core is made of can only be guessed, but scientists are pretty sure that it is there. They tested it by using the Juno space probe. The probe was launched in 2011 and it arrived at Jupiter in 2016. Since then, it has been orbiting Jupiter and has orbited the planet 28 times. It has many goals, but one of them is to test the solid core theory. By looking at how the velocity of the spacecraft was sped up or slowed down by Jupiter’s gravitational field, scientists could see how the mass is distributed within Jupiter. This showed them that Jupiter does have a solid core. It also showed them that the core is not just a solid ball, but more like a fuzzy sphere that spreads across half of Jupiter’s diameter. It seems as though the solid core has exploded. This could be explained by the way the core formed. If a huge proto-planet had hit the young Jupiter, then it could have shattered its solid core and made the fuzzy core we see today.

The scientist’s calculations showed that the core of Jupiter could have a mass that is 45 times that of planet Earth. That seems a lot, but it is still only 14% of Jupiter’s mass. The size of the planet is awe-inspiring.

So, Jupiter most likely does have a solid core. The way it formed makes a solid core most likely and experiments with the Juno space probe have proved it. Although, we will never be able to see the core. And this is what I learned today.

Photo By NASA, ESA, and A. Simon (Goddard Space Flight Center) – http://www.spacetelescope.org/images/heic1410a/

or https://commons.wikimedia.org/w/index.php?curid=32799232

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