In this episode, we answer a series of really excellent listener questions.   Mrs. White, a high school teacher, assigned our plate tectonics  episode to one of her A.P. classes and they came back with some great questions.  Here they are:1- how far have we drilled into the Earth and is there any hope of reading the mantle?  We have drilled about 12 km which is a tiny amount.  This took about 20 years to accomplish and the high temperatures inhibited drilling deeper.2- what instruments to we use to determine the thickness and structure of the core and mantle since we don't have any direct samples?  We study seismic waves traveling through the interior of the Earth.  3- what happens to the asthenosphere as a result of loss of magma during volcanic eruptions?  In answering this question, we discuss the misconceptions of what a magma chamber actually looks like.  It's a very complicated question that requires a complicated answer.Join us as we discuss the answers to these questions (we have drilled >12km deep into the Earth, which isn't very far!), discuss how the relate to recent scientific discoveries (what is a magma chamber anyways???), and talk about how we image the interior of the Earth using seismic waves!  Listener questions are always welcomed at PlanetGeo and they usually drive us to think about things more deeply, and sometimes end up with long answers!   ——————————————————Instagram: @planetgeocastTwitter: @planetgeocastFacebook: @planetgeocast Youtube: https://www.youtube.com/channel/UCJ_A82nOMu0nIvZto6zMPqgEmail: planetgeocast@gmail.comWebsite: https://planetgeocast.buzzsprout.com/