For years, researchers have been listening to Mars and the quakes that ripple through it, to understand the planet's internal structure and uncover its history. But often these results have left more questions than answers. Now, though, new research published in Nature reveals the composition and size of Mars's core, finding that it is much smaller than previously thought. Research Article: Khan et al. Research Article: Samuel et al. News and Views: Deep Mars is surprisingly soft Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday. Hosted on Acast. See acast.com/privacy for more information.