1. The problem statement, all variables and given/known data Describe what optical astronomers would consider the properties of an active galaxy and also describe what radio astronomers would describe as the properties of an active galaxy and explain how two sets of astronomers came up with these differing conclusions. 2. Relevant equations N/A 3. The attempt at a solution Ok. So optical astornomers would see a bright AGN and strong, broad emission lines suggesting high velocites for the gas within the galaxy. With the example of Centaurus A, optical astronomers would see an eliptical galaxy whereas radio astronomers would see jets of radiation feeding two lobes either side of the galaxy. What other properties would they be asking for? And it asks to describe in about 100 words how they could come to differeing conclusions. Well what more can I say other than one is viewing the galaxies at optical wavelengths whilst the other at radio wavelengths? Any ideas? Thanks.