What is a quasar ?

Answer 1

A quasi-stellar radio source, a quasar, is a very distant galactic nucleus that is extremely active as regards energy output. These sources just pour out electromagnetic energy in the form of light and radio waves. We also know that they are extremely far away because of the red shift associated with our observations of them. They are among the most distant objects we know, and they are moving away from us at very high speed, which is what gives their light the red shift. There is more information available at the Wikipedia article on the quasar, and a link is provide to the post. You'll find it below. Answer Imagine a light as bright as the light from a hundred galaxies. The light is being generated by stars and other material which are being dragged into a super sized black hole. As the material is being dragged into the black hole it is subject to huge friction which heats it up to millions of degrees. This kind of super powerful black hole is a quasar: the most powerful kind of object in the universe. By the time their light reaches us, they have long, long since sucked the life out of the galaxy they were feeding from.

A quasar will only exist in a really big galaxy... our galaxy, the milky way, isn't in any danger, because although we have a black hole at the centre of our galaxy; there is not enough matter to create the conditions for a quasar.


Many years ago, when modern Astronomy was still in its infancy, astronomers looked at all the lights in the sky and tried to figure out what they were. Some were stars, bright points of light, and some were smudgy, smeared objects; almost cloudy-looking. Those got the label "nebula", from the Latin word for "cloud". But it was difficult to determine how far away the objects were; the relative brightness was one of the few clues.

Later on, Edwin Hubble realized that the universe is expanding, and that most of the other galaxies were receding from us. By measuring the red-shift of the stars or galaxies, astronomers were able to determine how fast the objects were going, and because of the nature of the expansion, had a new way of determining distances.

There was one BIG problem. There were stars that appeared to be point-sources, so they weren't galaxies or nebulae, but were receding too quickly - and therefore too far away - for any star to be visible. There was just NO WAY for a star to be bright enough to be visible from that far away. From their distance and their brightness, they would need to pack the brightness of a galaxy into the size of a solar system, which was clearly beyond our (then) comprehension.

Astronomers named them "Quasi-Stellar Objects", and because most people are too lazy to use three words when one will do, shortened it to "quasar".

It took decades for some agreement to be reached on what the objects are that are so bright and yet so distant, but the current thinking is that a quasar is the accretion disk of gas and matter heated to incandescence by the gravity of a supermassive black hole in the center of what may have once been an "ordinary" galaxy.

Answer 2

A quasi-stellar radio source, a quasar, is a very distant galactic nucleus that is extremely active as regards energy output. These sources just pour out electromagnetic energy in the form of light and radio waves. We also know that they are extremely far away because of the red shift associated with our observations of them. They are among the most distant objects we know, and they are moving away from us at very high speed, which is what gives their light the red shift. There is more information available at the Wikipedia article on the quasar, and a link is provide to the post. You'll find it below. Answer Imagine a light as bright as the light from a hundred galaxies. The light is being generated by stars and other material which are being dragged into a super sized black hole. As the material is being dragged into the black hole it is subject to huge friction which heats it up to millions of degrees. This kind of super powerful black hole is a quasar: the most powerful kind of object in the universe. By the time their light reaches us, they have long, long since sucked the life out of the galaxy they were feeding from.

A quasar will only exist in a really big galaxy... our galaxy, the milky way, isn't in any danger, because although we have a black hole at the centre of our galaxy; there is not enough matter to create the conditions for a quasar.


Many years ago, when modern astronomy was still in its infancy, astronomers looked at all the lights in the sky and tried to figure out what they were. Some were stars, bright points of light, and some were smudgy, smeared objects; almost cloudy-looking. Those got the label "nebula", from the Latin word for "cloud". But it was difficult to determine how far away the objects were; the relative brightness was one of the few clues.

Later on, Edwin Hubble realized that the universe is expanding, and that most of the other galaxies were receding from us. By measuring the red-shift of the stars or galaxies, astronomers were able to determine how fast the objects were going, and because of the nature of the expansion, had a new way of determining distances.

There was one BIG problem. There were stars that appeared to be point-sources, so they weren't galaxies or nebulae, but were receding too quickly - and therefore too far away - for any star to be visible. There was just NO WAY for a star to be bright enough to be visible from that far away. From their distance and their brightness, they would need to pack the brightness of a galaxy into the size of a solar system, which was clearly beyond our (then) comprehension.

Astronomers named them "Quasi-Stellar Objects", and because most people are too lazy to use three words when one will do, shortened it to "quasar".

It took decades for some agreement to be reached on what the objects are that are so bright and yet so distant, but the current thinking is that a quasar is the accretion disk of gas and matter heated to incandescence by the gravity of a supermassive black hole in the center of what may have once been an "ordinary" galaxy.

Answer 3

Many years ago, when modern astronomy was still in its infancy, astronomers looked at all the lights in the sky and tried to figure out what they were. Some were stars, bright points of light, and some were smudgy, smeared objects; almost cloudy-looking. Those got the label "nebula", from the Latin word for "cloud". But it was difficult to determine how far away the objects were; the relative brightness was one of the few clues.

Later on, Edwin Hubble realized that the universe is expanding, and that most of the other galaxies were receding from us. By measuring the red-shift of the stars or galaxies, astronomers were able to determine how fast the objects were going, and because of the nature of the expansion, had a new way of determining distances.

There was one BIG problem. There were stars that appeared to be point-sources, so they weren't galaxies or nebulae, but were receding too quickly - and therefore too far away - for any star to be visible. There was just NO WAY for a star to be bright enough to be visible from that far away. From their distance and their brightness, they would need to pack the brightness of a galaxy into the size of a solar system, which was clearly beyond our (then) comprehension.

Astronomers named them "Quasi-Stellar Objects", and because most people are too lazy to use three words when one will do, shortened it to "quasar".

It took decades for some agreement to be reached on what the objects are that are so bright and yet so distant, but the current thinking is that a quasar is the accretion disk of gas and matter heated to incandescence by the gravity of a supermassive black hole in the center of what may have once been an "ordinary" galaxy.