Awards Earth processes poster

★ Murphy Quinlan, Maeve // Peek inside a planetesimal


A poster designed for a general audience, targeted towards primary school children, perhaps for display in a school library. The poster depicts an early Solar System planetesimal, with a cut-out showing the layers inside. Key terminology is embedded in contextual paragraphs and highlighted.


What is a planetesimal?

Planetesimals were small rocky little bodies in the early Solar System. Most of them either crashed into each other and stuck together to build the planets – this is called accretion!

Some didn’t survive this smashing and crashing, and were broken to pieces – the leftover scattered fragments formed the asteroid belt.

What is inside?

Some planetesimals heated up enough for the rock inside them to begin melting. Denser materials like iron sank down towards the centre to form a core. This is called differentiation. Lighter materials formed a mantle. Smaller pieces of rock crashed into the surface of the planetesimal, breaking it up into a dusty regolith.

Why are they interesting?

Planetesimals are known as planetary building blocks – they help us understand how the planets we see today came to be. We have some pieces of planetesimals here on Earth: some planetesimals were broken up into fragments in the asteroid belt, then little pieces of these asteroids were chipped off and delivered to Earth as meteorites. We can study these meteorites and figure out how big their parent body was!

Image description

The poster features a large cartoon of a planetesimal with a dimpled, crater-pocked surface. A chunk is cut out of the planetesimal, revealing the layering inside: a small purple and red core, and a mantle in swirling orange. These layers are labelled. The background is a purple with brush stroke and ink spatter textures.

Maeve Murphy Quinlan

Maeve is a planetary science PhD student studying the evolution of planetesimals in the early Solar System and tying these bodies to meteorite samples, tying together numerical modelling techniques with analytical cosmochemistry. Maeve is passionate about outreach in schools.


Twitter: @thisismaeveq

Organisation: Institute of Geophysics and Tectonics, University of Leeds