Questions and Answers
When we look out into space we look backward in time.
True
'Fixed' stars never move.
False
0 hours of right ascension is marked off on the celestial equator.
True
What causes the seasons?
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If you are called a Capricorn, what constellation may the sun at birth have been in for 2/3rds of the cases?
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Name an object that does not retrograde.
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What is the reason the same side of the moon is always pointing toward the Earth?
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What did ancients predating 1,000 BC evidently know about?
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Why do Venus and Mercury never vary by more than a certain angle from the sun?
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Copernicus' theory of planetary motion was more complex but better than Ptolemy's.
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Planets move in strictly circular orbits about the sun.
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The planet Pluto is moving fastest when it is farthest from the sun.
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Outer planets have shorter orbital periods than inner planets.
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The greater the steepness of an inclined plane, the slower a ball rolls down it.
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A kiloparsec is a million parsecs.
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Who was the first in recorded history to realize that stars are actually like our sun?
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What is the distance between foci of an ellipse divided by the widest diameter called?
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What does the eccentricity of an ellipse measure?
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When does a comet move slowest?
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Tycho Brahe was noted most for his:
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Which of the following did Copernicus not assert?
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Motion is relative to the observer.
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Mass is the ratio of the net force on an object divided by its associated acceleration.
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The gravity between two objects depends more on one of their masses than the distance between them.
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In considering motion, what is the perspective of a coordinate system tied to an observer?
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What happens to an astronaut after pushing off from the outside of a spacecraft?
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A skier pushes backward with the ski poles. What law is responsible for the skier consequently accelerating forward?
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What did Galileo discover that was similar to Earth's features on an extraterrestrial body?
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A rocket with twice the force of thrust, but half the mass will have what acceleration?
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What mathematician gave Einstein his curved space idea, which led to his gravity discoveries?
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In Einstein's Special Theory, nothing can go faster than what?
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When one approaches the speed of light, what happens to time?
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Einstein's General Relativity has been proven by deviations from Newton's Law of Gravity which occur near the sun and other massive objects.
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Time dilation (slowing) can occur near a massive object or by going near the speed of light.
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Light is an electromagnetic wave.
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Light has rest mass.
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Light has a wavelength and a frequency which are related.
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A refractor or refracting telescope has mirrors.
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As you come closer to a distant object with a telescope, the rays of light coming from it become less parallel.
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If we could bend light, how many times would light go around the Earth in a minute?
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When we heat up a single-element gas like hydrogen in a tube on Earth, what do we get off?
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A photon is what?
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What is a black-body curve's most important revelation?
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Doppler shifting toward lower frequency because an object is moving away from us is called what?
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To see x-rays from space, we need what type of telescope?
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What does a lens use to focus rays?
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In a city near a major observatory, using street lamps with a smaller wavelength spread will help reduce what?
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Refractors have the following major disadvantages:
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What is the name of the satellite that discovered the first black hole, meaning 'freedom' in Swahili?
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What is the principle involved when light bends entering at an angle an interface between glass and water?
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Study Notes
Time and Space
- Observing distant celestial objects allows us to see them as they were in the past due to the time taken for light to reach Earth.
- Stars classified as 'fixed' actually move, contradicting the historical view of their immobility.
- Right ascension is measured, with 0 hours marked on the celestial equator.
Earth's Characteristics and Astrology
- The tilt of Earth's axis is responsible for changing seasons.
- Astrological definitions indicate that individuals identified as Capricorn may have their sun in Sagittarius two-thirds of the time at birth.
Celestial Motion
- The Moon does not exhibit retrograde motion from Earth's perspective.
- Tidal locking causes the same side of the Moon to always face Earth.
- Ancient civilizations were aware of the precession cycle of the equinoxes.
Planetary Motion and Theories
- Venus and Mercury maintain close angular proximity to the Sun due to their orbits and size.
- Copernicus’s theory of planetary motion was more sophisticated compared to Ptolemy’s but still flawed; he mistakenly supported some views of Pythagoras.
Orbital Mechanics
- Planets do not solely follow circular orbits around the Sun.
- Pluto's speed is greatest when it is closest to the Sun, not when it is farthest.
- Outer planets take longer to orbit the Sun than inner planets.
Physics Fundamentals
- Eccentricity measures how much an orbit deviates from being circular, while the distance between the foci is a critical factor.
- Motion is considered relative to the observer's frame of reference.
Newton's Laws and Gravity
- An astronaut who pushes off a spacecraft will continue in orbit around Earth due to inertia.
- Skier's acceleration forward through pole push exemplifies Newton's third law combined with his second law.
Historical Contributions
- Galileo was the first to discover mountains on the Moon, noting Earth-like features on extraterrestrial bodies.
- Riemann influenced Einstein's concepts of curved space, affecting the understanding of gravity.
Relativity and Light
- According to Einstein’s Special Theory, the speed of light is the universal speed limit.
- Time experiences dilation as one approaches the speed of light or in the presence of massive objects, corroborated by Einstein's General Relativity.
Light Properties and Telescope Function
- Light is an electromagnetic wave, possessing wavelength and frequency but no rest mass.
- Refracting telescopes utilize lenses for focusing light, while reflecting telescopes use mirrors.
Observational Astronomy
- Achieving visibility of X-rays from space necessitates the use of satellite telescopes.
- Light pollution can be reduced through careful selection of street lighting in urban areas.
Discoveries in Astronomy
- The Uhuru satellite was pivotal in discovering the first black hole, with its name meaning 'freedom' in Swahili.
- Black-body radiation offers insight into the temperature of stars and other celestial bodies, while Doppler redshift indicates an object moving away.
Diffraction and Refraction
- Refraction is the bending of light when passing through different mediums, such as glass into water.
- Chromatic aberration is a major disadvantage in refracting telescopes, alongside challenges in manufacturing large models.
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Description
Test your knowledge with these flashcards on key concepts in Astronomy. Explore fascinating facts such as the nature of fixed stars, the significance of right ascension, and how Earth's axial tilt affects the seasons.
