text: how to count the tangential velocity? i was wondering about how to count it, what is it exactly. can we say that some objects move with the velocity bigger than c? eg. when a supernova explodes, we can observate it from a distance on a screen. when we add more details about the situation and the shape of the screen, we can say about the velocities bigger than c. what are those details? :) hi. there is a star being watched very closely by astronomers because it may be a new type of supernovae. the light 'echoes' from reflecting gas and dust seem to move at a speed greater than 'c'. this is not due to anything actually moving. just the lit up areas expand in a tangential fashion. : http://www.habitablezone.com/space/messages/444552.html