On the left, we have a representation of Jupiter’s aurora, and on the right, a representation of Earth’s aurora. And of course the Earth was magnified almost 10 times, otherwise it would look very insignificant compared to its older sister.
These are 3D representations, but are based on real satellite data. In addition to the visible and familiar surface, the aurora borealis, represented by blue, has been added. These auroras were observed at ultraviolet wavelengths by Juno probe For Jupiter By satellite image for the land.
It’s important to explain how our science communication images are created and to explain that no, you wouldn’t see this if you could observe these stars with the naked eye, just to avoid misunderstandings. It is, of course, not a matter of cheating, on the contrary, of showing what is there, but our senses hide from us.
Read more: How are sky images formed? In the footsteps of the pioneering Hubble telescope
How are twilights born?
The aurora borealis is the result of the impact of charged particles (usually electrons) on the top of the planet’s atmosphere. After this effect, the atoms and molecules of the atmosphere emit light in a series of wavelengths (of colors, if you prefer) of their own. These auroras are called “polar” because the planet’s magnetic field directs these charged particles from the magnetosphere toward the polar regions. To the north we have the aurora borealis and to the south the australian aurora.[Près de 70 000 lecteurs font confiance à la newsletter de The Conversation pour mieux comprendre les grands enjeux du monde. Abonnez-vous aujourd’hui]
A planet’s magnetosphere is a “bubble” in space, where the planet’s magnetic field controls the motion of charged particles, not that of the sun. Most of the particles in the magnetosphere revolve around magnetic field lines and oscillate along them. But a whole series of phenomena, such as excitation of different waves, the presence of electric currents or even “magnetic reconnection”, particles can be deposited in the polar atmosphere and create auroras. The aurora borealis thus forms a picture of the motion of particles in this magnetosphere.
The magnetospheres of Earth and Jupiter are fundamentally different
Planet Earth is very sensitive to changes in the solar wind. In particular, when the magnetic field of the solar wind and that of the Earth are aligned, but in opposite directions, at the front of the magnetosphere, a phenomenon called magnetic reconnection occurs, which allows solar particles to rush into the Earth’s magnetosphere.
Read more: The aurora borealis: what they tell us about climate and space weather
Jupiter’s magnetosphere is populated primarily by particles from the volcanoes of Io. These electrons and sulfur and oxygen ions are then carried away by the planet’s magnetic field and begin to spin at the same speed as Jupiter, accumulating along Io’s orbit and forming what’s called “Ayo Hoop”. These particles then slowly escape, causing waves, electric currents, and magnetic reconnection.
So it is clear that the magnetospheres of Earth and Jupiter do not work at all in the same way. Therefore, the aurora borealis of Jupiter has many differences from the aurora borealis on Earth.
Study the aurora borealis to better understand the planets
Take, for example, the leftmost oblong spot in Jupiter’s aurora borealis. It’s called the auroral imprint of Io. It’s caused by the vortices that Io generates in her self-made torus.
On the other hand, there is an almost identical structure in the two images: it is this strange shape in the form of an eye, in the lower right part on Jupiter and in the lower part relative to Earth. We call them “Storm of Dawn” on Jupiter and “Auroral storm” on the earth. Both are caused by a sudden reshaping of the back of the magnetosphere (magnetic tail). In fact, although there are very different reasons, one due to matter emitted by Io and the other due to the solar wind, magnetospheres can accumulate mass and energy in this magnetic tail, until it cracks and similarly releases large amounts of particles into the aurora. Regions.
This exercise is called comparative planetary science, and it makes it possible, as we have just seen, to isolate universal phenomena from the peculiarities of each planet. By observing these distant planets, we learn as much about these alien worlds as we do about our own.