Astronomy Colloquium

  Tycho Brahe's observations of a supernova in 1572 challenged the dogma that the celestial realm was unchanging.  440 years later we have once again seen the light that Tycho saw: some of the light from the 1572 supernova is reflected off dust and is only now reaching Earth. These light echoes, as well as ones detected from other historic events like Cas A and Eta Carinae's Great Eruption, give us a very rare opportunity in astronomy: direct observation of the cause (the explosion/eruption) and the effect (the remnant) of the same  astronomical event.  Furthermore, in some cases we can compare light echoes at different angles around a remnant, and thus investigate  possible asymmetry in the explosion.  I will discuss how the unprecedented view at these exciting events with light echoes allows  us to unravel some of their secrets.