Cool Worlds Lab guest Dr Sarah Ballard from MIT explains how observing dead stars (white dwarfs) can reveal the makeup of exoplanets and even exoplanetesimals! Be sure to follow Sarah on Twitter @hubbahubble and check out her website at http://www.drsarahballard.com. ::More about this Video:: ► Farihi et al. (2013), "Evidence for Water in the Rocky Debris of a Disrupted Extrasolar Minor Planet": http://arxiv.org/abs/1310.3269 ► Xu et al. (2014), "Elemental Compositions of Two Extrasolar Rocky Planetesimals": http://arxiv.org/abs/1401.4252 ► Vanderburg et al. (2015), "A disintegrating minor planet transiting a white dwarf": http://arxiv.org/abs/1510.06387 ► Outro music by Taylor Davis: https://www.youtube.com/watch?v=dl9kI1yQKZk ::Playlists For Channel:: Latest Cool Worlds Videos ► http://bit.ly/NewCoolWorlds Cool Worlds Research ► http://bit.ly/CoolWorldsResearch Guest Videos ► http://bit.ly/CoolWorldsGuests Q&A Videos ► http://bit.ly/CoolWorldsQA Science of TV/Film ► http://bit.ly/ScienceMovies ::Follow us:: SUBSCRIBE to the channel http://bit.ly/CoolWorldsSubscribe Cool Worlds Lab http://coolworlds.astro.columbia.edu Twitter https://twitter.com/david_kipping Instagram https://www.instagram.com/cool.worlds THANKS FOR WATCHING!!