The earth’s mantle is just like a lava lamp, with the lava rising slowly upwards. The earth’s core is the lamp that warms the lava. This is one of the many similes Earth scientist Arwen Deuss from Utrecht University uses to explain to year 8 of the Utrechtse Schoolvereniging (USV) what the centre of the earth looks like. And to outline some of the extraordinary discoveries she has made. Interesting additional piece of information: certainly half of the pupils had heard of a lava lamp.
Meet the Professor 2019
“A travel journal straight through the earth”
During the opening of the Meet the Professor event in University Hall, the professors were subjected to a brainteasing quiz, presented by pupils from De Jazzsingel primary school. All 140 professors subsequently got on their bikes and headed for a primary school in Utrecht. With a large shopping bag filled with homemade models of the earth hanging from her handlebars, Arwen cycled to the Utrechtse Schoolvereniging (USV). “The pupils asked so many questions, and with such enthusiasm, that I hardly had time for my own story,” she explains afterwards.
Discover what you like the most
Arwen starts her lesson with a question: “Who has felt an earthquake?” A few pupils raise their hands. After a brief explanation of tectonic plates and molten iron, Arwen tells the class about her favourite holiday destination: the volcano on Stromboli in the Mediterranean Sea, just above the ‘toe’ of the Italian ‘boot’. “The volcano erupts every 20 minutes, and you can climb it. But that is actually very dangerous.” Arwen has always been interested in how the earth works, and knew that she wanted to be a professor as early as year 7. This is precisely why she thinks it is so great and important to kindle children’s enthusiasm. “Before you become a professor, you need to discover what you like the most, you see,” she tells year 8.
A wave through the class
A few years ago, Arwen discovered that the inner core of the earth consists of solidified iron, and not molten iron, as previously thought. She is keen to share this discovery with the class, but first, the pupils need to find out for themselves what a shock wave from an earthquake is. Standing in a long line across the classroom, they recreate two such shock waves: one of them by giving the next person in the line a little push in sequence to create a wave – a bit like at a football stadium. To see into the very heart of the earth, you need to be able to analyse these waves, explains Arwen.
The earth has a solid inner core
“The shape of a seismogram shows us everything that the vibrations passed through, and therefore what the centre of the earth looks like,” she continues. “You see, a seismogram is like the travel journal of a vibration passing through the earth.” Arwen explains that by applying this concept, she became the first person to prove that the earth has a solid inner core, which is very slowly expanding because the earth’s core is cooling. “When will the iron be solidify completely?” asks a pupil. “That will take another billion years, or longer,” is Arwen’s answer. “So that is not really a problem for us. There are more pressing issues, such as climate change, the effects of which we will notice sooner.”
Fun and informative
Thanks to the enthusiasm of both Arwen and the pupils, the lesson overruns. But nobody minds. According to their teacher Anne, the pupils have never before been so quiet. The pupils thought the lesson was fun and informative, and that Arwen was a captivating storyteller. Of course, the entire class wanted their photograph taken with the professor.