• Photo by Nicolas J Leclercq on Unsplash
  • Photo by Nicolas Tissot on Unsplash
  • Photo by NASA on Unsplash
  • Photo by USGS on Unsplash

Ganymede: The largest icy moon of Jupiter

Following up on our last blog about the icy moons of Jupiter, in this blog we start off with understanding the largest moon of the planet and our Solar System, Ganymede! Although we have only a few measurements from the moon through the Galileo and Juno missions orbiting Jupiter, we have quite a lot of information from them.

Ganymede is a very unique moon. It is the only moon we know of that is capable of generating its own magnetic field, possibly through a dynamo. This means that there is some conducting liquid in which convection is taking place that is producing a magnetic field of the order of ~103 nT. This dynamo is expected to be an iron and iron sulphide alloy.

While the most important and interesting insight about Ganymede is the dynamo, another fascinating feature is the presence of a subsurface ocean. However, we are still unsure if the field we observed was from an ocean or just part of the dynamo signal. When we model magnetic field data of the moon, both these possibilities arise and hence to confirm which of them are true, we would require more data from around the moon.

Once we have a wealth of measurements from future missions, we would be able to better model the magnetic field as well as other observations like the gravity field which will help us better understand its interior structure. In the meantime, drop your questions about Ganymede below and let us know what you are curious to find about the moon!

Image: Ganymede from Galileo. Credit: NASA.

Shivangi Sharan is a postdoctoral research associate at Imperial College London, working on prioritising the research that will be carried out using the JUICE magnetometer data. Previously, she has worked on the interior of Mars and Jupiter using their magnetic observations. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

The icy moons of Jupiter

Jupiter is a giant ball of gas which is 10 times larger than the planet we live on. Naturally, the magnetic field it produces is also stronger, more than 20 times Earth's magnetic field!

While we need to understand Earth's field for our day to day tasks like navigation, we study Jupiter's field to understand the evolution of the Solar System. One major consequence of the strong field of Jupiter is its effect on the Galilean moons.

The Galilean moons, namely Io, Europa, Ganymede and Callisto are the biggest four moons that orbit Jupiter. Making use of the limited data we have from them, we believe that the moons have a conducting liquid near the surface. This liquid is most likely an ocean of water and salts except in Io where we think its a magma ocean. The evidence for this primarily comes from magnetic field measurements of the moons. 

Magnetic field provides a unique way to study the interior of the object that produces it. Thanks to it and the satellites that take the instrument to measure it, we can study the electromagnetic induction in the moons of Jupiter sitting in our offices on Earth. When there is a periodically varying field near a body which has conducting material, induction takes places inside the body which produces a magnetic field. In this case, the time varying field is the large magnetic field of Jupiter and the conducting material is the subsurface ocean of the moons. If we study the induced field from the satellite measurements, we can find properties like the depth, conductivity and thickness of these oceans. All we need are magnetic observations from near the moons. While it seems easy, we do have to wait a few years before ESA's Jupiter ICy Moons Explorer (JUICE) and NASA's Europa Clipper missions can reach and transmit their observations from the Jovian system!

Image credits: ESA

Shivangi Sharan is a postdoctoral research associate at Imperial College London, working on prioritising the research that will be carried out using the JUICE magnetometer data. Previously, she has worked on the interior of Mars and Jupiter using their magnetic observations. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

Space News

Let's have a glance at the upcoming Space missions' news!

In 2024, there are some milestones to be achieved for different Space missions. 

Find a sneak peak below.

1) Intuitive Machines 1 - NASA lunar lander launch in mid-February

2) Chang'e 6 - Chinese lunar sample return mission launch in May

3) Bepi Colombo - ESA mission fourth and fifth Mercury flyby on September 5 and December 2

4) Martian Moon eXploration - JAXA Phobos sample return launch in September

5) Europa Clipper - NASA Jupiter orbiter launch in October

6) Hera - ESA asteroids mission launch in October

7) VIPER - NASA lunar lander launch in November

Source: NASA

Image Credit: ESA- D. Ducros 

Sara and her science journey

Hi and Happy New Year to all the readers of this wonderful blog. I am Sara Gasparini, PhD student at the University of Bergen in Norway and with great enthusiasm and gratitude I recently became co-chair of the IAGA Education and Outreach committee. I am from the Italian alps, and I attained my Master’s degree in Physics at the Norwegian University of Science and Technology in Trondheim. I wrote my Master’s thesis in Svalbard about the first SuperDARN (Super Dual Auroral Network) radar’s results. Living in Svalbard was a lifetime experience and a great opportunity to improve both my scientific and life skills. I received a Bachelor’s degree from the University of Turin and my thesis showed different approaches for solving the Schrödinger’s equation for molecules far more complex than the hydrogen atom. I am very passionate about life and science and my curiosity has brought me to always learn about different topics. Outreach and education have always been two of my major interests besides science. What I love about outreach is the ability to amaze young minds and people not in the field. It challenges you to think about why we are doing what we do. What motivates our passion and quest for knowledge? What I love about education is that a good mentor and great teachings is all you need to feed your enthusiasm and not let it go to waste. Bright minds are motivated with new challenges and inspiring environments that great mentors know how to provide. And I would love to be that great mentor one day for young students. Passion and charisma is what warms the hearts of us human beings.

This is the SuperDARN radar in Svalbard just before it fell in 2018. This radar is part of a network of more than 30 coherent scatter radars and the radar I used for my Master Thesis to deepen the knowledge on ionospheric electrodynamics. 

My PhD research focuses on the study of the auroral oval, trying to identify the physical processes that give the auroral oval the shape it has. At high latitudes in each hemisphere there is an almost constantly present ring of aurora, known as the auroral oval. The auroral oval is sensitive to conditions in the solar wind—in particular the solar wind’s embedded “interplanetary magnetic field.” Changes in the interplanetary magnetic field have an effect on the rate of magnetic reconnection on the Earth’s dayside and ultimately leads to changes in the auroral oval morphology/topology. Understanding these changes allows for the study of the physical processes and time scales that dictate the shape and dynamics of the large-scale auroral oval. My PhD thesis seeks to understand the mechanisms which are responsible for the growth and contraction of the auroral oval, determining its shape and its changes over time.

My PhD work in the Dynamics of the Asymmetric Geospace group at the University of Bergen currently consists of working with data assimilation. In particular I work with IMAGE (Imager for Magnetopause-to-Aurora Global exploration) satellite images. Satellite images are a good tool to study large scale dynamics of the auroral oval because they continuously show the global response of the ionosphere to particle precipitation, usually the cause of visible aurora and they enable us to follow the shape of the aurora. Precipitating charged particles—protons and electrons with energies varying from approximately 100 eV to 20 keV—travel along the magnetic field lines from the magnetosphere into the upper-atmosphere and their collisions with the ionospheric neutrals cause auroral emissions. This not only creates beautiful patterns in the sky, which have astonished humans since we looked up the skies, but also gives us a tool for keeping track of the precipitating particles and studying their collective behavior in the
ionosphere. Satellite images are also a tool to derive ionospheric conductances which are fundamental when assimilating data using the basic ionospheric physics equations such as the ionospheric Ohm’s law. In my research I combine images from IMAGE with SuperDARN data and ground-based magnetometers data to globally quantify ionospheric convection. Ionospheric convection measurements together with the images allow me to understand the shape and the temporal evolution of the auroral oval. Moreover, they are fundamental quantities to calculate reconnection electric fields. Reconnection electric fields are the key parameters we use to understand the interaction between the Sun and the Earth’s magnetosphere. Hence, my work is devoted to interpreting reconnection electric fields and their associated uncertainties to infer new knowledge.

Here I am preparing the KHO Svalbard auroral cameras to make them ready for the auroral season. In the background is the EISCAT Svalbard incoherent scatter radar.

In my private life I do a lot of meditation. A calm mind is a temple for great ideas. I enjoy discovering new places and being in nature. When I am not hiking or in the middle of outdoor activities, I enjoy swimming at the pool as I generally enjoy water activities very much. I swim in the ocean all year round, even when the fjord temperatures are close to zero in the winter. In general, I like every kind of sport. Skiing is one of my favorite winter sports along with ice climbing, and every week I practice ballet. Determination and perseverance is what I train during my ballet classes. By doing a lot of sports I also strengthen the idea that our mind is our friend if we are healthy and in a healthy environment. As the latins used to say, “Mens sana in corpore sano”. From time to time I like to read about philosophy. Marcus Aurelius is one of my favorite philosophers. I am also passionate about learning new languages and other cultures. As I am a very curious person, I like to try new things, therefore new hobbies are always on the list!

Here I give you a quote from Marcus Aurelius. I like to remind myself of this everyday as we are here to enjoy life and be passionate about what we do. It is also a reminder to practice loving kindness towards ourselves and every being. If you would like to connect and share your experiences feel free to reach out, and if you would like to read one of my outreach articles follow the link below.

“Dwell on the beauty of life. Watch the stars, and see yourself running with them.”


2024 IAGA Events

With our wishes for the new year, here are the IAGA events that will take place in 2024-

    May 6-10 : 12th International Workshop on Long-Term Changes and Trends in the Atmosphere (TRENDS 2024) : Joint IAGA and IAMAS in Ourense, Galicia, Spain.

    May 13-17 : Course on Operational Space Weather Fundamentals : L’Aquila, Italy.

    June 2-7 : The Combined ANGWIN/VCAIS Meeting : Fredericton, New Brunswick, Canada.

    June 23-2818th Symposium of SEDI : Great Barrington, MA, USA.

    June 30- July 518th Castle Meeting - New trends on Paleo-, Rock- and Environmental Magnetism : Utrecht, Netherlands.

    September 7-1326th Electromagnetic Induction WorkshopBeppu, Japan.

    September 30- October 411th VLF and ELF Remote Sensing of the Ionosphere and Magnetosphere (VERSIM) Meeting : Breckenridge CO, USA.

    October 6-9Electromagnetic Studies of Earthquakes and Volcanoes (EMSEV 2024) : Joint IAGA, IASPEI, IAVCEI in Chania, Greece.

    October 31- November 6XXth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition and ProcessingVassouras, RJ, Brazil.

Other than these events, IAGA science will have sessions in other conferences like EGU, COSPAR and AGU. Keep a look out at our Twitter channel for more info and let us know if we missed any event in the comments.

🎉 Have a happy and exciting new year! 🎉

'Geoscience Connections' Documentary

While we already informed you about the 'Geoscience Connections' project where short introduction and science videos of Early Career Researchers are showcased every week on YouTube in our older blog, we have more news! The project awarded by IUGG (International Union of Geodesy and Geophysics) to the joint IAGA-IASPEI proposal consists of a documentary and short videos showcasing the work done by the community of scientists that fall under the 8 associations of IUGG. And.... the documentary is out now on IAGA and IUGG Youtube channels!

Under the project, two videos are available- 'Earth Human Connections' and 'Geoscience Connections'.

'Earth Human Connections' is a short animated movie that shows the evolution of Earth through an analogy between humans and Earth. The timeline starts from the formation of our planet and across billions of years when humans became Earth’s inhabitants. On the one hand, the intelligent human brain allowed for the development of various brilliant technologies and a complex society. On the other hand, humans have participated in the uncontrolled exploitation of natural resources, and are thought to have caused many problems to other living beings on our planet. This movie also won the 'Audience Award' at the Braga Science Film Festival.

'Geoscience Connections' is a documentary that leads you through a fascinating journey through the Earth’s history, explained by eight early-career researchers who represent each international association of IUGG. The geoscientists help us to better understand Earth processes, bring us hope for the problems humanity faces and solutions towards a more sustainable Earth. The early career scientists that were involved in the documentary include- 

International Association of Geodesy (IAG) - Hugo Lecomte 
International Association of Geomagnetism and Aeronomy (IAGA) - Hannah Rogers 
International Association of Seismology and Physics of the Earth's Interior (IASPEI) - María Isaba 
International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) - Kyriaki Drymoni 
International Association for the Physical Sciences of the Oceans (IAPSO) - Malin Ödalen 
International Association of Hydrological Sciences (IAHS) - Bertil Nlend 
International Association of Meteorology and Atmospheric Sciences (IAMAS) - Jing Li 
International Association of Cryospheric Sciences (IACS) - Erik Loebel 

Narrator - Elodie Kendall

We hope to reach a wide audience through this initiative and spread scientific knowledge to the general public. We also hope it would strengthen the networking between the different IUGG associations, especially for upcoming and early career researchers. 

Please have a look and share if you learnt something new! Head over to our YouTube channel for more content for kids, public and researchers.


Unraveling Earth's Ancient Geography: Advancements in Paleomagnetic Analysis and Plate Reconstructions

Plate tectonics plays a crucial role in shaping Earth's geography, impacting the evolution of life and climate. To really understand the long-term evolution of Earth’s systems, we need to quantify the past motions of the tectonic plates. Plate reconstructions have been crucial in figuring out an enormous array of Earth processes.

Conventionally, past plate motions are inferred from physical characteristics of the sea floor, specifically its magnetic anomalies and fracture zones. Together, those features have allowed the construction of global plate reconstructions back to the Cretaceous (~130 Ma). But the inherent nature of plate tectonics masks its own origin story: oceanic lithosphere records are progressively destroyed by subduction, so they cannot be used in deeper time. Before 130 Ma, plate motions can only be quantified through the study of paleomagnetism.

Over long time scales (~105-106 years), the geomagnetic field can be approximated by a geocentric axial dipole (GAD), where the vertical field component is specifically linked to latitude and the horizontal component consistently points north. This means that if a rock can record the direction of the paleomagnetic field during its formation and the GAD hypothesis remains valid (at least back to ~540 Ma), we can establish its original paleolatitude and azimuthal orientation! However, analytical limitations have so-far prevented us from using this tool to its full potential. For example, owing to the axial symmetry of the Earth’s magnetic field, the determination of paleolongitude from paleomagnetic data –although theoretically possible– cannot be constrained. Paleolongitude has thus remained the greatest uncertainty in pre-Cretaceous plate reconstructions (top panel figure).

Paleomagnetic records are collected from individual rock samples and subsequently grouped to develop global-scale paths called apparent polar wander (APW) paths. These APWPs represent the time-dependent position of Earth's spin axis relative to a given block of lithosphere or continent.

Hypothetical APWP track (filled dots).
Top panel: Conventional paleomagnetic reconstruction where paleolongitude remains unconstrained.
Bottom Panel: the APWP segment traces a small circle, the centre of which represents the Euler vector. Rotations about Euler poles can completely define plate motion so PEP analysis yields east-west motion.

Euler’s theorem states that any displacement across the surface of a sphere can be represented by a rotation about an axis (i.e. Euler vector). Consequently, if a continent rotates about a fixed axis, the corresponding paleomagnetic poles (i.e. APWP segment) will trace an arc which can be defined by a small circle, the centre of which represents the Euler vector. The inversion of paleomagnetic data to retrieve Euler vectors – or paleomagnetic Euler pole (PEP) analysis – is of particular interest because it offers the possibility to recover full kinematic descriptions of past plate motion. Because an Euler vector can fully express the kinematics of a continent, if paleomagnetic data can be used to compute Euler vectors describing a given plate’s history of motion, its paleolongitude is determinable!

This exciting method could overcome the paleolongitudinal indetermination of paleomagnetism, but despite being first conceptually introduced more than half a century ago has seen limited application. This appears to be due, at least in part, to the fact that paleomagnetic data is inherently noisy, with noise coming from both intrinsic (geomagnetic secular variation) and extrinsic (e.g. measurement errors, erroneous age assignments in rocks, inclination shallowing, etc.) uncertainties. For instance, current APWPs describe plate motion in 10 Ma steps, yielding a crude description of plate latitudinal and azimuthal motion.

Recent advances in APWPs construction methods have demonstrated that through new methodologies and computational methods, it is possible to generate APW paths with unprecedented spatial and temporal resolution (~1Ma). These new methods may offer new insights into Earth's deep time evolution. Great things are on the horizon!

Leandro Gallo is a Maria Skłodowska-Curie postdoctoral fellow at the Center for Planetary Habitability (PHAB), a Center of Excellence funded by the Norwegian Research Council and hosted at the University of Oslo (UiO), Norway. His research focus is reconstructing the long-term changes in the ancient spatial configuration of continents (paleogeography). A major focus of this research is on paleomagnetic data synthesis tools, combining data-analysis, data-science and statistics to constrain polar wander through deep time.