Planetary Magnetic Fields : Gas Giants

Ever wondered how the beautiful auroras we see are formed? You are right, it’s due to the energetic particles carried along with the solar wind from the sun, that enter the magnetic field shield, called the magnetosphere of the planet, interacts there and collects at the poles. Why at the poles? Because that’s how the field lines travel. But it doesn’t just happen on Earth. And it doesn’t just emit visible light spectrum, at least on the outer planets.

Interior models of the giant planets. Image : NASA/Lunar and Planetary Institute

The gas and ice giants of our Solar system - Jupiter, Saturn, Uranus and Neptune - have extremely large magnetic fields and magnetospheres. Their interiors are unlike the interior of the terrestrial planets. They are mostly composed of gases and have a small solid core. Their magnetic fields are similar to that of Earth, i.e, dominantly dipolar, but the magnitudes are much larger than the terrestrial value. 

The interiors of Jupiter and Saturn consist of hydrogen and helium in different forms. Jupiter has the largest magnetic field in the Solar system that is assumed to be generated from the metallic hydrogen in its interior. The magnetosphere is so large that its tail almost reaches Saturn. The metallic hydrogen of Saturn is considered smaller in size comparatively and thus produces a lower magnetic field, but still much larger than Earth’s. The dipole magnetic field axis and the rotation axis almost align.

Magnetic field of the outer planets. Image : Stevenson 2018

The ice giants, Uranus and Neptune, have no metallic hydrogen but have molecular hydrogen and compounds like methane and ammonia in their interior. Uranus has an off-centered field. It rotates on its side due to its large tilt and its magnetic and rotation axes make a 59 degrees angle between them. The magnetic field and magnetosphere of Neptune is similar except that the planet is not as tilted.

Read about the magnetic fields of terrestrial planets here.

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Shivangi Sharan is a second year PhD student at the Laboratory of Planetology and Geodynamics in France. Her research focusses on the study of the magnetic field of Mars and to infer its internal structure from it. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

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2021 IAGA-IASPEI Conference

Attend the upcoming conference - http://www.iaga-iaspei-india2021.in/

As anyone working in science knows, conferences are a great way to understand what researchers in your field all over the world are currently working on and an even greater way to meet with them and interact professionally as well as personally.

IAGA holds General Assemblies every two years for scientists to come together and share their work to the community. The reports on IAGA activities are also shared in the meetings in order to take future decisions on the scientific, administrative and financial policies. Previous meetings have been held in different parts of the world like Italy, Canada and South Africa. This year, the meeting was supposed to take place in August in India but due to the pandemic, it will be held completely online. IAGA is conducting a joint assembly with IASPEI, which is the International Association of Seismology and Physics of the Earth’s Interior. 

Don’t miss out on the opportunity to attend and learn about the activities of the Magnetic and Seismic communities and register here!

There would be scientific sessions of the different IAGA Divisions and also joint sessions between them. All topics covered by the researchers working on different themes will be on display through poster and oral presentations. The programme also includes lectures from distinguished scientists in the field. Details for the sessions and lectures can be found in the links below.

Click here to see the scientific program by time and date so that you can choose the ones you are interested in! The business meetings to discuss about the progress and future work of the IAGA Divisions and Commissions can also be found in the link.

All information about the sessions can be found here.

All information about the lectures can be found here.

A Geoscience Information for Teachers (GIFT) Workshop will be conducted on the topic "Understanding the Changing Earth". Click here for the schedule and programme.

The previous meetings and workshops conducted by IAGA can be found here.

IAGA also conducts summer schools before its General Assemblies. Know about them from our previous blog here.

Digitization of Kosmos Missions

Geophysical Center of the Russian Academy of Sciences performed digitization of IZMIRAN catalogues containing historical data of magnetic satellite missions Kosmos‐49 (1964) and Kosmos‐321 (1970). 

External view of Kosmos-321 and Kosmos-356 from Krasnoperov et al. 2020.

Totally 17300 measured values are available for Kosmos‐49 mission, covering homogeneously 75% of the Earth's surface between 49° north and south latitude. About 5000 measured values are available for Kosmos‐321 mission, covering homogeneously 94% of the Earth's surface between 71° north and south latitude. 

The mission of Kosmos‐26 and Kosmos‐49 confirmed the possibility of using Earth’s magnetic field data for determination of spacecraft orientation. The obtained geomagnetic data justified the evidence of propagation of magnetic anomalies, associated with the structure and tectonics of the Earth’s crust, to the heights of low‐ orbiting satellites. 

In 2020, these results were presented to the scientific community in the ESSD data paper “Early Soviet satellite magnetic field measurements in the years 1964 and 1970” by Krasnoperov R., Peregoudov D., Lukianova R., Soloviev A., Dzeboev B. (https://doi.org/10.5194/essd‐12‐555‐2020). The value of the presented data is emphasized by the fact that older and publicly available global satellite data on the Earth's magnetic field in digital form for that period are rare and hard to acquire.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.