Galaxy Flashcard

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What is a spiral galaxy?

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A spiral galaxy is a type of galaxy characterized by a flat, rotating disk containing stars, gas, and dust, along with a central concentration of stars known as the bulge.

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What are the main components of a spiral galaxy?

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The main components of a spiral galaxy include the central bulge, spiral arms, and a surrounding halo of dark matter.

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What distinguishes elliptical galaxies from spiral galaxies?

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Elliptical galaxies are characterized by an ellipsoidal shape and lack the distinct spiral structure found in spiral galaxies. They generally contain older stars and less gas and dust.

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What is an irregular galaxy?

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An irregular galaxy is a type of galaxy that does not have a distinct regular shape, often appearing chaotic in structure. They typically contain young stars and significant amounts of gas and dust.

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How do galaxies form?

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Galaxies form from the gravitational attraction of matter in the universe, leading to the coalescence of gas and dust into stars and clusters, which eventually evolve into galaxies.

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What is the role of dark matter in galaxies?

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Dark matter is an unseen form of matter that does not emit light or energy, and it plays a crucial role in the formation and structure of galaxies by providing the necessary gravitational pull.

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What is the Milky Way?

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The Milky Way is the galaxy that contains our solar system, characterized as a barred spiral galaxy with a central bulge and several spiral arms.

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What is the significance of the Hubble classification scheme?

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The Hubble classification scheme categorizes galaxies into different types (spiral, elliptical, irregular) based on their appearance, helping astronomers understand their formation and evolution.

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What is a galaxy cluster?

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A galaxy cluster is a large group of galaxies held together by gravity, often containing hundreds or thousands of galaxies.

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What is the difference between active and inactive galaxies?

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Active galaxies emit significant amounts of energy, often due to supermassive black holes at their centers, while inactive galaxies do not exhibit such high levels of energy output.