Mercury – The Overlooked Planet

Mercury is the smallest planet in the solar system and the closest to the Sun, yet it's one of the least visited worlds we know, studied up close by only two spacecraft in fifty years. This episode explores why a scorching, airless little planet is so hard to reach, what its oversized iron core and ice-filled polar craters tell us, and how its orbit helped confirm Einstein's general relativity.

You'll come away understanding why Mercury has the largest day-night temperature swing of any planet, what a spin-orbit resonance is and why a single Mercury day outlasts two Mercury years, why the planet's disproportionately large iron core is still not fully explained, how permanently shadowed polar craters can hide water ice on the solar system's hottest small world, why Mercury's orbit helped confirm general relativity, and why gravity itself makes Mercury one of the hardest planets to actually reach.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: NASA – MESSENGER mission science summaries; ESA/JAXA – BepiColombo mission pages; NASA Solar System Exploration – Mercury fact sheets; Scientific American – features on Mercury's core and spin-orbit resonance.