Chapter 1827: Crater Ocean

Chapter 1827 Crater Ocean

There are currently two theories to explain the formation of the polar cap, one is considered to be caused by the diffusion of ice bodies at high latitudes, and the other is believed to be caused by the bombardment of plasma ice bodies in outer space. Galileo's observations favor the latter theory.

Ganymede may have been created by the accretion of the Jupiter subnebula - the disk of gas and dust that surrounded Jupiter after its formation. Ganymede's accretion process lasted about 10,000 years , there is a sharp distinction between the darker Nicholson zone and the brighter Harpagia trough.

Much shorter than Callisto's 100,000 years. By the time the Galilean moons began to form, the Jupiter subnebula contained relatively little gas; this resulted in Callisto's long accretion time. On the contrary, since Ganymede was formed immediately after Jupiter, the subnebula was relatively dense at this time, so its accretion took a shorter time.

The relatively short formation time allows less escape of the heat generated during the accretion process, which leads to the melting of the ice body and the differentiation of Ganymede's internal structure: that is, the rock and ice body separate from each other, and the rock sinks into the star body The center forms the inner core. In this respect, Ganymede differs from Callisto, which, due to its long formation time, has exhausted its accretion heat and thus is unable to melt ice and differentiate its internal structure at an early stage. This hypothesis explains why two moons that are so close in mass and composition look so different.

After its formation, Ganymede's inner core still retains most of the heat formed during the accretion and differentiation processes, and it only slowly releases a small amount of heat into the icy mantle layer, just like the operation of a thermal battery. Then, the mantle conducts heat to the surface of the star through convection. Soon the radioactive elements contained in the rock began to decay, and the heat generated further heated the inner core, which intensified the differentiation of its internal structure, eventually forming an iron-ferrous sulfide core and a silicate mantle. So far, Ganymede's internal structure has completely differentiated.

In contrast, the radioactive heat generated by Callisto, which has not differentiated its internal structure, can only cause convection in its icy interior, which effectively cools the star and prevents large-scale ice melting and internal structure. rapid differentiation of ice and rocks, and at most it can only cause partial differentiation of ice and rock. Today, Ganymede's cooling process is still very slow. The heat released from the inner core and silicate mantle allows Ganymede's subsurface ocean to exist, while only the slowly cooling, flowing iron-iron sulfide core still drives thermal convection within the star and maintains the magnetosphere. existence of the circle. The external heat flux of Ganymede is probably higher than that of Callisto.

After Zhao Zhongyao told Feifei some knowledge about Ganymede. Their spacecraft has already flown over Ganymede.

Now their spacecraft is more than 100 kilometers away from Ganymede. From this height, the entire surface of Ganymede can be seen clearly. Ganymede is also a planet full of craters. After all, in the entire solar system, except for the terrain on the earth, due to the changes in the sea, there are not many craters to be seen. Almost all other planets in the solar system are covered with large and small craters.

After all, after billions of years of history, these planets will leave many craters no matter which planet it is. After all, there are many small celestial bodies in the entire solar system. The number of these small celestial bodies can be said to be countless.

After Ganymede has experienced a long history of billions of years, it has naturally encountered countless meteorite impact accidents. Of course, most meteorites are very small. Only very few meteorites are very large.

Feifei looked at Ganymede who was close in front of him and said, 'Dad, then we should go to that place now to find the sixth amethyst gemstone. Do you feel that this sixth amethyst gemstone will be somewhere on this planet. '

After hearing Feifei's words, Zhao Zhongyao said, "According to past experience, wherever amethyst gemstones exist, there should be life." Moreover, most of them are in the huge craters of some planets.

There are also many craters on Ganymede. If we want to look for amethyst gems, we should also look for a huge crater. I feel that the sixth amethyst gem is in a very huge crater. '

'What Dad said is, can we go to find a huge crater now? ’ Said Feifei.

'That's right, we just need to find a huge crater now. Zhao Zhongyao said the same.

So, Zhao Zhongyao took Feifei to sit in the spaceship, and he could look for the huge crater on Ganymede.

But after they searched for a while, Feifei looked at Zhao Zhongyao again and said, 'Dad, then we should go to that crater to find the amethyst gem. You feel that this amethyst gem will be in that crater. '

Zhao Zhongyao thought for a while and said, 'On Ganymede, there is a very famous crater. This crater is called the Galileo crater. We, we can first go to this crater to have a look. '

'Okay, let's go to this crater first to have a look! ’ After hearing what Dad said, Feifei said like this.

So, Zhao Zhongyao drove the spacecraft again and flew towards the Galileo crater. Soon, they flew over the huge crater.

After reaching the sky above this huge crater, Zhao Zhongyao was surprised to see that there was a huge ocean at the bottom of this huge crater.

As soon as he saw this huge ocean, Zhao Zhongyao felt that the amethyst gem they were looking for must be in this ocean.

Feifei also said very happily, 'Dad, this crater

There is an ocean in it. From this point of view, the amethyst gemstone we are looking for must be in this ocean. '

'That's right, let's start descending into this Galileo crater now! We'll soon find the sixth amethyst gem. ’ Feifei also said happily.

So, Zhao Zhongyao drove the spaceship to this Galileo crater again.

This Galileo crater has a diameter of hundreds of kilometers and is the largest crater on Ganymede. Probably formed two billion years ago. It was formed by the impact of an asteroid with a diameter of about ten kilometers.

It is precisely because of the large size of this asteroid that when it hit Ganymede, it hit a very huge crater.