Jupiter, definition and study. A-Z index of Cognitio.
Jupiter is the fifth planet of the solar system in order of distance from the Sun and the largest of the entire planetary system: its mass corresponds to 2,468 times the sum of those of all the other planets put together.
It is classified, like Saturn, Uranus and Neptune, as a gaseous giant.
Jupiter has a composition similar to that of the Sun: in fact it consists mainly of hydrogen and helium with small amounts of other compounds, such as ammonia, methane and water. It is believed that the planet possesses a multilayered structure, with a solid core, presumably of a rocky nature and made up of carbon and iron silicates, above which a metal hydrogen mantle and a vast atmospheric cover gravitate, exerting high pressures on it.
The external atmosphere is characterized by numerous bands and zones of shades varying from cream to brown, dotted with cyclonic formations, among which the large red spot stands out.
Jupiter appears to the naked eye as a very bright whitish astro due to its high albedo. It is the fourth most brilliant object in the sky, after the Sun, the Moon and Venus with which, when the latter is undetectable, it shares the role of “morning star” or “evening star”.
Since 1973, many automatic probes have visited the planet, both as a study objective and as an intermediate stage, to exploit its powerful gravitational sling effect to head into the more distant regions of the solar system. The last probe to reach Jupiter was the New Horizons, which, directed towards Pluto and the objects of the Kuiper belt, performed a fly by of the planet to exploit its gravity; the closest approach was February 28, 2007. NASA designed a probe for the study of Jupiter from a polar orbit; baptized Juno, was launched in August 2011 and arrived near the planet in July 2016.
The possible presence of an ocean of liquid water on the Europa, Ganymede and Callisto satellites has led to a growing interest in a close study of the icy satellites of the external solar system. The great luminosity of Jupiter, which makes it clearly visible in the night sky, has made it the object of numerous religious cults by ancient civilizations, first the Mesopotamian civilizations.
For the Babylonians, the planet represented Marduk, the first of the gods and the creator of man.
The NASA probe is investigating the enigmas of the interior of the great planet of the Solar System. Unveiling the first discoveries. Juno, the NASA probe in orbit around Jupiter since July 2016, has managed, with its instruments, to “pierce” the surface of the great planet so as to “observe” what until now had never been able to other probes nor to space or ground telescopes: the probe’s remote gaze has penetrated many thousands of kilometers below the surface of the clouds.
A first surprising element regards the nucleus of the gaseous planet, which seems to be very small and poorly defined in its borders, compared to what was thought until today. Like other giant planets and like all the terrestrial planets it is hypothesized that Jupiter also has a core of iron and silicates, but how large it is and as borders with the upper layer composed of hydrogen, it remains a mystery to solve – except for the fact that now we know that this border is rather hazy.
Then there is a strange feature that concerns the gravitational field of Jupiter, which is not homogeneous in all its parts. This is due to the fact that the planet’s hydrogen gas flows from the depths to the surface in an asymmetric way. It is an unforeseen fact, but it would give meaning to the in-homogeneity of the gravitational field.
Another question for researchers is the rotation speed of the planet: is it homogeneous from the surface to the nucleus or does it very with depth? Some answers are now available. By studying the manner in which gravity is manifested, it has been established that the material that makes up the planet rotates faster at about 3,000 kilometers of depth, below the surface of the atmosphere. Now the question is how fast is this flow of material and if the gases that make up Jupiter actually form a kind of “matrioske”, where each level differs from the others by the rotation speed. Scientists are now analyzing the gravity values recorded by the Juno probe, which will also use them to try to calculate the thickness of the large red spot, which according to some data seems to have roots hundreds of kilometers lower, and perhaps even more. In addition to this, and always in relation to the composition of the planet, in the data of Juno scientists seek answers to other mysterious phenomena, such as the non-uniformity of the magnetic field of Jupiter.
Another curious element are the cyclones observed at the poles of the planet, which seem to dance around an invisible center. Before this mission nobody suspected the existence of these phenomena, because they had never been able to observe the poles of the planet, while Juno – in its orbit of 53 days – has a trajectory that led her to fly over them. Around the “north pole” there are 8 cyclones, while at the opposite pole there are five cyclones. The mystery lies in the fact that according to our models of the atmosphere of Jupiter could not persist that much, because there would be no conditions to feed them … Instead they are there and it seems that nothing can dissolve them. The horizontal bands instead are the best known feature of the great planet: they are the result of rising and falling of material from the atmosphere towards the gaseous surface of the planet, and of very high winds at high altitudes. Up to now it has not been known whether these bands are confined to a very superficial level or whether they also affect the deep atmosphere of the planet. This was just one of the questions we wanted to answer: there is still a lot of data to analyze, but at the moment the second hypothesis seems to prevail.
Jupiter, definition and study. A-Z index of Cognitio.
© ALL RIGHTS RESERVED
To open the video click on the image, good view from your Alessandro Brizzi.