Clusters of stars, nebulae and others scattered throughout the universe
The term Galaxy is designated by each of the groupings of stars, nebulae, interstellar dust, planets, particles and gases that are scattered throughout the universe and that are gravitationally bound together..
Meanwhile, within each galaxy the number of stars that form it is variable, from dwarfs to giants, in addition, there are different substructures such as nebulae, star clusters and multiple star systems.
Milky Way, the galaxy of planet earth
From the earth, the planet we inhabit, all the stars that we see with the naked eye belong to our own galaxy, popularly known as the Milky Way.
The Milky Way belongs to a group made up of forty known galaxies known as the Local Group, it has a mass of 1012 solar masses and an average diameter that reaches 100,000 light years and scientists estimate that the Earth's galaxy contains between 200,000 and 400,000 stars.
The stars that are part of a galaxy maintain a gravitational interaction and orbit around a common center, in our case, the Milky Way, the function of common center is performed by the Sun.
Intergalactic space
On the other hand, intergalactic space is made up of a gas, which has an average density lower than one atom per cubic meter. Generally, it is given that galaxies have various aggregates that are known by the name of clusters, which in turn may form larger aggregates, called supeclusters.
Classification of galaxies
Depending on the shape they present, galaxies are classified into different types: Irregular Galaxies, those that show disturbances caused by the gravitational attraction of the galaxies that are next to them, as neighbors, the Elliptical Galaxies, are characterized by having an ellipse shape and Spiral Galaxies, because they have a circular shape with curved arms, wrapped in powder.
Wide use in the cinema
Without a doubt we can say that the concept of galaxy is of recurrent use in our language and this is given not only because these groupings are a fundamental part of our universe and then when we are part of one of them we are involved and linked with them but also because the concept has been popularized in other areas besides astronomy.
In the seventh art, for example, to cite one of the contexts in which these groupings have been used the most and are used as a framework for science fiction stories. Many of the highest grossing movies and TV shows enrolled in this genre show galaxies and develop their stories in them.
Star Wars, the famous saga directed by George Lucas, takes place precisely in a fictional galaxy and tells the story of human characters and their interaction with other non-human beings that come from other planets and satellites that belong to the galaxy. And this is one of the many stories of cinema that speak and happen in the galaxies.
Surely the fervent interest that the subject arouses among the general public contributes to the fact that authors and directors of this genre repeatedly address the theme of galaxies.
Colloquial use
On the other hand, in colloquial use, the concept is widely used and is linked to the distance with which humans consider galaxies. Because although we are part of them, in our case of the Milky Way, we cannot visualize them as we can with the stars, one of its fundamental components.
So, when a person is not attentive or paying attention to something that is being said or is developing, or as a basic characteristic of his personality, he never pays attention or interest to almost anything, only to what matters to him, it is often said that it is in another galaxy. "My brother lives in another galaxy, he never knows anything about what happens in the family."
