Questions and Answers
How are spiral galaxies and elliptical galaxies different?
They have arms where elliptical galaxies do not and they are not flattened into a disk shape.
What do the letters A, B, and C indicate in reference to spiral galaxies?
What do the numbers represent in the classification of elliptical galaxies?
0 is more rounded; the higher the number, the more stretched out or elongated the galaxy becomes.
What is the shape of a galaxy that has the classification S0?
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What are two classifications for spiral galaxies, and how do they differ?
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How might the Milky Way galaxy be classified? Why is its classification uncertain?
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How are galaxies that are neither spiral nor elliptical classified? Give an example of this type of galaxy.
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Study Notes
Differences Between Spiral and Elliptical Galaxies
- Spiral galaxies feature arms that extend from a central disk, while elliptical galaxies do not have arms and are not flattened into a disk shape.
Classification of Spiral Galaxies
- Letters "a," "b," and "c" indicate the spacing of the arms in spiral galaxies:
- "A": Arms are closely packed together.
- "B": Arms are spaced at an average distance.
- "C": Arms are far apart from each other.
Classification of Elliptical Galaxies
- Numbers represent the shape of elliptical galaxies:
- "0" indicates a more rounded shape.
- Higher numbers signify increasing elongation and stretchiness of the galaxy.
Characteristics of S0 Galaxies
- Galaxies classified as S0 have a disk shape but lack spiral arms.
Types of Spiral Galaxies
- There are two classifications of spiral galaxies:
- Barred spirals have a central bar shape connecting the arms.
- Normal spirals do not feature this bar structure.
Classification of the Milky Way
- The Milky Way is classified as a spiral galaxy.
- Its classification remains uncertain because humans have never observed the galaxy from an external vantage point.
Irregular Galaxies
- Galaxies that do not fall into the spiral or elliptical categories are classified as irregular galaxies, denoted as "Irr."
- An example of irregular galaxies includes the Magellanic Clouds.
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Description
Test your knowledge about the differences between spiral and elliptical galaxies. This quiz covers their characteristics and classifications, including the meaning of letters and numbers in their classification systems.
