Neptune is similar in size to Uranus; But it is not exactly its twin version, but it is more voluminous and at the same time smaller. Militzer’s model shows a thinner atmosphere and a larger core (about the size of Mars) for Neptune; But both Uranus and Neptune have the same layers of water and hydrocarbons. Militzer said in a statement:
Now we have a good theory that shows why Uranus and Neptune have different fields that are also very different from planets like Earth, Jupiter and Saturn. We did not know this information before. They behave like water and oil, except that oil is placed below because it has lost its hydrogen.
According to Voyager 2 measurements, the magnetic fields of Uranus and Neptune are irregular and differ greatly from Earth’s north-south field. According to Militzer, the cause of this problem can be found in the lack of convection in these two worlds. The hydrocarbon layer is placed in a fixed shape and almost like a plastic polymer, so it does not allow convection. Militzer further explains:
We think that there is an ocean in which hydrogen is combined and has a high conductivity, which is necessary for a magnetic field.
However, the mentioned ocean has a pressure 60,000 times that of the Earth’s surface, so it may act like a supercritical fluid (a mixture of gas and liquid) rather than water on Earth. Like oil and water, this water is separated from the carbon-rich layer below that separates the ocean from the planet’s core.
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Previously, scientists thought that the interiors of Uranus and Neptune were more mixed. What’s new, Militzer says, is that the water is separated from the carbon; But Uranus and Neptune may have formed with less hydrogen than Jupiter and Saturn due to their distance from the Sun.
The blue layer is responsible for producing the irregular magnetic fields of Uranus and Neptune. Dr. Militzer’s hypothesis could explain a key difference between Jupiter and Saturn and Uranus and Neptune. A large part of Jupiter and Saturn is hydrogen. The first step to understanding the solar system was the difference between gas giants and rocky planets. Then we come to the difference between hydrogen giants and ice giants.
The above finding can provide good data for returning to Uranus in the next decade. The Uranus orbiter can carry instruments to measure the internal space and magnetic field of Uranus, which are able to measure the internal structure and magnetic field of Uranus and find out the existence of a water layer on this planet.
