Armin Rest, CFA, Harvard University

Topic: "An Astronomical Time Machine: Light Echoes from Ancient Supernovae"  (Video)

ABSTRACT: Tycho Brahe's observations of a supernova in 1572 challenged the Church dogma that the celestial realm was unchanging. 438 years later we have once again seen the light that Tycho saw: some of the light from the 1572 supernova is reflected off dust clouds and is only now reaching Earth. These light echoes, as well as ones detected from other supernovae, give us a very rare opportunity in astronomy: direct observation of the cause (the supernova explosion) and the effect (the supernova remnant) of the same astronomical event. Furthermore, in some cases we can compare light echoes at different angles around a supernova remnant, and thus investigate possible asymmetry in the supernova explosion. I will discuss several examples where we are using this technique to "transport ourselves backwards in time" to study ancient supernova events.