Fossil galaxy group
Okay kiddo, so a group of galaxies means different galaxies hanging out together in space. A fossil galaxy group is a special kind of group where the galaxies have been hanging out together for a very, very long time.
It is like when you have a group of friends, but you have been friends for so many years that you’ve all grown old together. Just like that, the galaxies in a fossil group have been together for billions of years!
And do you know what happens when you’re hanging out with friends for a long time? You start to affect each other. In the same way, the galaxies in a fossil group have been affecting each other's movements for billions of years.
Eventually, the galaxies start moving so slow that they stop coming together and slowly drifting apart. This is called isolation. So, a fossil group is a group of galaxies that used to be active, but now they are quiet and far apart from each other.
It is like when you have a group of friends, but you have been friends for so many years that you’ve all grown old together. Just like that, the galaxies in a fossil group have been together for billions of years!
And do you know what happens when you’re hanging out with friends for a long time? You start to affect each other. In the same way, the galaxies in a fossil group have been affecting each other's movements for billions of years.
Eventually, the galaxies start moving so slow that they stop coming together and slowly drifting apart. This is called isolation. So, a fossil group is a group of galaxies that used to be active, but now they are quiet and far apart from each other.
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