Jupiter's aurora borealis is different from Earth's

• Jupiter's aurora borealis has many differences from that of our Earth, according to our partner The Conversation.

• This phenomenon is due to Jupiter's magnetosphere which is essentially "populated" with electrons and sulfur and oxygen ions from the volcanoes of its moon Io.

• This analysis was conducted by Bertrand Bonfond, science researcher at the University of Liège (Belgium).

On the left, we have a representation of the auroras of Jupiter, and on the right, a representation of the auroras of the earth.

And of course, the earth has been enlarged almost 10 times, otherwise it would seem very insignificant compared to its big sister.

These are 3D representations, but based on real satellite data.

In addition to the visible and familiar surface, the polar auroras have been added, represented in blue.

These auroras were observed in ultraviolet wavelengths by the Juno probe for Jupiter and by the IMAGE satellite for Earth.

It is important to explain how we create our science communication images and to explain that no, you would not see this if you could observe these stars with the naked eye, just to avoid misunderstandings.

It is of course not a question of cheating, but on the contrary of showing what exists, but that our senses hide from us.

How are the auroras born?

Auroras are the result of the impact of charged particles (usually electrons) on the top of a planet's atmosphere.

Following this impact, the atoms and molecules of the atmosphere emit light in a series of wavelengths (of colors, if you prefer) which are specific to them.

These auroras are called "polar" because the planet's magnetic field guides these charged particles from the magnetosphere towards the polar regions.

To the north we have the aurora borealis and to the south the aurora australis.

A planet's magnetosphere is a "bubble" in space, where the movement of charged particles is controlled by the planet's magnetic field, rather than that of the sun.

Most particles in a magnetosphere simply revolve around magnetic field lines and oscillate along them.

But a whole series of phenomena, such as excitation by various waves, the presence of electric currents or even “magnetic reconnection”, can precipitate particles in the polar atmosphere and create auroras.

The auroras therefore constitute an image of the movement of the particles in this magnetosphere.

​The magnetospheres of Earth and Jupiter are radically different

That of the Earth is very sensitive to variations 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, on the front of the magnetosphere, a phenomenon occurs, called magnetic reconnection, which allows solar particles to rush into the Earth's magnetosphere.

Jupiter's magnetosphere is mainly populated by particles from the volcanoes of its moon 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 spins, accumulating along Io's orbit and forming what is known as the "torus of Io".

These particles will then slowly escape, causing a procession of waves, electric currents and magnetic reconnections.

It is therefore clear that the magnetospheres of the Earth and Jupiter do not function at all in the same way.

Therefore, the auroras of Jupiter have many differences from the auroras on Earth.

​Studying the auroras to better understand the planets

Take for example the leftmost elongated spot in Jupiter's aurora.

It's called the auroral imprint of Io.

It is caused by the eddies that Io generates in the torus that she herself created.

On the other hand, there is a structure which is almost identical in the two images: it is this strange shape in the shape of an eye, at the bottom right on Jupiter and at the bottom for the Earth.

They are called "dawn storm" on Jupiter and "auroral substorm" on Earth.

Both are caused by sudden reconfiguration of the rear part of the magnetosphere (the magnetotail).

Indeed, although for totally different reasons, one because of the material ejected from Io and the other because of the solar wind, the two magnetospheres can accumulate mass and energy in this magnetotail, until it cracks and similarly releases large amounts of particles into the auroral zones.

Our file "JUPITER"

This exercise is called comparative planetology, and it makes it possible, as we have just seen, to isolate universal phenomena from the peculiarities specific to each planet.

By observing these distant planets, we learn almost as much about these exotic worlds as about our own planet.

Science

Space: How do we know that our universe is expanding?

Science

Asteroids: Why exploring them will help protect Earth (and understand the origin of the solar system)

This analysis was written by Bertrand Bonfond, FNRS qualified researcher at the University of Liège (Belgium).

Access to this content has been blocked to respect your choice of consent

By clicking on "

", you accept the deposit of cookies by external services and will thus have access to the content of our partners

I ACCEPT

And to better remunerate 20 Minutes, do not hesitate to accept all cookies, even for one day only, via our "I accept for today" button in the banner below.

More information on the Cookie Management Policy page.

Declaration of interests

• Science

• Video

• The Conversation

• Space

• Jupiter

• Astronomy

• Solar system

• Earth