Despite what scientists believed so far, the process that gives rise to Jupiter’s auroras is not the same as that of our planet’s auroras. In fact, the data collected by Juno, the NASA probe that studies the planet Jupiter, suggests the origin of its powerful auroras (100 times more energetic than terrestrial ones) is more similar to that of intermediate auroras on Earth than that of the strong ones.
Not all auroras are the same, the intensity varies from one to another: the stronger, the brighter they emit. And the brightness of Jupiter’s auroras is much more powerful than that of terrestrial ones. For this reason, the researchers had assumed that their explanation would be the same as that of the strongest auroras on Earth. “For many years we have believed that we understood Jupiter’s auroras,” acknowledges John Clarke, an astrophysicist at Boston University. “But then Juno got there, crossed the magnetic fields above an active aurora, and did not detect what we expected, ” explains the researcher.
On Earth, polar auroras (known as borealis in the northern hemisphere and southern in the southern hemisphere) are produced by the collision between electrical particles that come from the Sun (known as the solar wind) and the magnetic field of our planet. This electromagnetic phenomenon gives rise to three types of auroras: discrete and intense, caused by the downward acceleration of electrons along the magnetic field; faint and diffuse auroras, caused by scattering of electrons in the magnetic field; and finally, the broadband ones, which have an intermediate intensity, caused by a turbulent acceleration of the electrons.
The brightness of Jupiter’s auroras are so intense that scientists have always considered that their origin would be the same as that of the discrete ones on Earth, the downward acceleration of electrons in line. And indeed, these acceleration processes have been detected but Juno has shown that they are not the cause of the powerful auroras of Jupiter , according to the study published in the journal Nature . “On Earth, these electrical potentials cause the most intense auroras but they are not the source of the most intense aurora on Jupiter and this is a surprise to us,” explains Barry Mauk, lead author of the study.
The mechanism of intermediate auroras on Earth, electrons with turbulent acceleration, is what causes the most intense auroras on Jupiter. This acceleration in Jupiter is caused by the instability of the electrical potential of such a large planet, generating the characteristic light of the aurora. These results provide new knowledge about the electromagnetic interaction of the planets with their environment but show the need to continue with the investigations.
“We often use models of the Earth’s atmosphere and magnetic field as starting points to describe other planets. But the Juno observations force us to review everything we assumed, especially if we try to understand exoplanets, many of which look alike. more to Jupiter than to Earth “, concludes Mauk in the study.
References:
BH Mauk. Discrete and broadband electron acceleration in Jupiter’s powerful aurora. Nature 549, 66–69 (2017). Doi: 10.1038 / nature23648
Image: NASA
