Questions and Answers
Match each type of galaxy to its observed characteristics:
Barred spiral galaxy = Slanted spiral Dwarf elliptical = Small yellow dot Giant elliptical = Big yellow dot Unbarred spiral = Centered spiral
Match the galaxy classification on Hubble's tuning fork:
Elliptical = All the way on the left Unbarred spirals = On the top Barred spirals = On the bottom Irregular = All the way on the right
What is the general motion for the stars in an elliptical galaxy?
Which measurement would be used to determine if galaxies are moving toward or away from the Milky Way?
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Hubble's law was discovered using measurements of two properties of a galaxy: ____ and ____.
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How fast would a galaxy at a distance of 225 Mpc be moving away from the Earth?
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Supermassive black holes occur in most, perhaps all, large galaxies.
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Evidence of a supermassive black hole at the center of the Milky Way comes from:
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Currently, where are star formation rates highest?
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A higher density will cause the universe's expansion to:
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What does the cosmological principle state?
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Astronomers observe that nearly all galaxies are moving away from the Milky Way, suggesting that an observer in a distant galaxy would make the same observation.
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Sort the following statements as either correct or incorrect:
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Cosmological redshifts are calculated from observations of spectral lines from:
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What does the cosmic microwave background radiation (CMB) tell us about the early universe?
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Where in the universe did the Big Bang take place?
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Why are the paper clips getting farther apart with time in Hubble's law analogy?
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If there is enough mass in the universe such that the density is higher than the critical density, the universe will eventually collapse.
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Which of the following are properties of the young universe, as revealed by the cosmic microwave background?
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If a universe is dominated by dark energy, it will expand forever.
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Study Notes
Galaxy Types and Classifications
- Barred spiral galaxies have slanted spiral structures.
- Dwarf elliptical galaxies appear as small yellow dots.
- Giant elliptical galaxies are characterized by large yellow dots.
- Unbarred spiral galaxies feature a centered spiral structure.
- Hubble's tuning fork classifies galaxies as follows: elliptical (left), unbarred spirals (top), barred spirals (bottom), irregular (right).
Stellar Motion in Galaxies
- In spiral galaxies, the bulge contains stars that orbit irregularly in all directions.
- The disk of spiral galaxies features stars that move together in a single direction.
- Elliptical galaxies predominantly exhibit stars with irregular orbits in all directions.
Hubble's Law and Galaxy Movement
- The Doppler shift of spectral lines is used to determine if galaxies are moving toward or away from the Milky Way.
- Hubble's law relies on two measurements: distance and recession velocity of galaxies.
- A galaxy located 225 Mpc away is estimated to be receding at a speed of approximately 15,000 km/s.
Supermassive Black Holes and Star Formation
- Most large galaxies, possibly all, harbor supermassive black holes at their centers.
- Evidence for a supermassive black hole in the Milky Way comes from multiple sources confirming its presence.
- Star formation rates are currently highest within spiral galaxies.
Universe Density and Expansion
- A higher density of the universe contributes to a slower expansion rate over time.
- The cosmological principle asserts consistency in the rules governing the universe throughout all regions.
- Observations show that nearly all galaxies are moving away from the Milky Way, indicating that distant observers would note the same phenomenon.
Expansion of Space
- The expansion of space creates distance between galaxies, which remain fixed in time.
- Incorrect notions include galaxies shrinking, moving through space, or spreading into pre-existing space.
- Cosmological redshifts derive from observations of the spectra of entire galaxies.
Cosmic Microwave Background and Universe Properties
- The cosmic microwave background radiation indicates that the early universe experienced much higher temperatures than now.
- The Big Bang occurred everywhere in the universe, rather than a specific location.
- Properties of the young universe included high density, uniformity on large scales, and high temperature.
Future of the Universe
- If the universe has a mass density exceeding the critical density, it is predicted to eventually collapse.
- A universe dominated by dark energy will continue to expand indefinitely.
- The analogy of paper clips moving apart due to a stretching rubber band illustrates Hubble's law's principle of cosmic expansion.
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Description
Test your knowledge on various types of galaxies and their characteristics, including barred spiral, dwarf elliptical, and giant elliptical galaxies. This quiz also covers stellar motion within galaxies and Hubble's Law related to galaxy movement. Challenge yourself to identify and classify galaxy types based on their unique features.
