Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
Welcome to our Physics lesson on What are Galaxies?, this is the first lesson of our suite of physics lessons covering the topic of Galaxies and Hierarchic Structures in the Universe, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
There are billions of stars in the universe. They are not distributed in space in a uniform way. We have explained in the previous tutorials that stars tend to get closer to each other over time because of gravitational forces that have an attractive nature. Hence, various groups of stars from the most remote to those in clusters are formed in the sky.
Astronomers realized long ago that stars are organized in groups according to certain hierarchies, similar to the hierarchic structure of humans, who are first grouped and organized in families, then in local communities (villages, towns, cities, etc.), then in nations, and ultimately in international organizations such as ONU.
Likewise, stars have their own families which are components of larger groups called galaxies. A number of galaxies that are close to each other form groups of galaxies, groups are organized in supergroups and all supergroups of galaxies taken together form the Universe. We will explain each of them but our main focus will be on galaxies as these are the most consolidated groups of stars.
By definition, a galaxy is a huge collection of gas, dust, and billions of stars and their solar systems held together by gravity.
You have reached the end of Physics lesson 22.6.1 What are Galaxies?. There are 7 lessons in this physics tutorial covering Galaxies and Hierarchic Structures in the Universe, you can access all the lessons from this tutorial below.
Enjoy the "What are Galaxies?" physics lesson? People who liked the "Galaxies and Hierarchic Structures in the Universe lesson found the following resources useful:
Please provide a rating, it takes seconds and helps us to keep this resource free for all to use
We hope you found this Physics lesson "Galaxies and Hierarchic Structures in the Universe" useful. If you did it would be great if you could spare the time to rate this physics lesson (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.