to what we imagine the fate of light once it enters the event horizon. For example, if I get sucked into a black hole once I cross the event horizon you will not be able to hear me scream and I will pulled out and stretched out like spaghetti! natasha_qurban: how we can detect blackholes? Kevin: There are two basic ways we can tell whether there's a black hole. Black holes are of course dark by definition - not even light escapes them! atci: Several studies have estimated the size and mass of the Andromeda Galaxy. When The Milky Way and Andromeda collide, what situation is likely to occur between the two centers? Ezequiel: That's a great question. What we think that will happen is that once Andromeda and the Milky Way start colliding, the gas that is floating around in both galaxies will start falling to the center and eventually falling onto the resulting black hole. So, while the andromeda's BH is ~10 million solar masses and the milky way's 4, the resulting BH after the merger sequence can be 100 million solar masses or larger. Nathan: When a black hole is described as being so many solar masses, is this referring to the mass of the singularity? riyanatarajan: Solar masses is a unit of measure of the mass content of the black hole. NaVaM10: Speak spanish or no? Ezequiel: Yo hablo espaol... alguna pregunta? Saludos! natasha_qurban: what is black hole? Kevin: The first way we detect black holes