The irregular galaxy is one of three types of galaxies. Galaxies are classified according to their shape. An irregular galaxy lacks a distinctive shape. On the other hand, spiral galaxies have a spiral shape. And, elliptical galaxies are ovoid. In contrast, irregular galaxies come in many different and unique shapes.
Shapes
Irregular galaxies have many different shapes. Their unusual shapes are often the result of two galaxies interacting with one another. As the universe expands, two galaxies may move close to one another. When this happens, the gravitational pull of each galaxy begins to distort one another’s shape.
In an extreme instance, two galaxies may actually collide with one another. This will greatly distort their original shapes. The two galaxies may even merge into one new galaxy.
Age and Color
There is no set pattern with respect to age. Some irregular galaxies are young. Others are much older.
Because their ages vary, irregular galaxies do not have a set color. In contrast, young spiral galaxies are usually blue. On the other hand, older elliptical galaxies are usually red. Therefore, irregular galaxies range in color from blue to red.
Origin
Transition to an Elliptical Galaxy: One theory is that irregular galaxies are in transition. For example, when two medium sized spiral galaxies collide with one another, the initial result may be an irregular galaxy. However, over time, the final shape may be an elliptical galaxy.
Ring Galaxy: The ring galaxy is considered irregular. Ring galaxies are formed when a small galaxy passes through the center of a large galaxy. The gravitational interaction distorts the shape of both galaxies. The smaller galaxy pushes galactic materials outwards and creates a ring shape in the larger galaxy.
Reflections
Vocabulary
- spiral galaxy
- elliptical galaxy
- gravity
Notes
- Irregular galaxies have no set shape or color.
- Irregular galaxies are created when two galaxies interact with one another.
- The ring galaxy is considered an irregular shape.
