Question

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astronomy honors midterm exam study guide
this study guide includes a list and outline of all skills and topics from units 1 through 5 that will appear on the midterm exam. complete and submit the study guide as your last extra credit opportunity of the semester. in addition to the study guide other useful tools for review or the slides on canvas, past tests and quizzes, and the reading/question worksheets we have done throughout the semester
exam format:

• the exam consists of 75 multiple choice questions.
• there are 14 questions from each unit except for unit 5 which has 10 questions.
• students will be given the entire exam period to complete the exam, although, you may not need to use the entire time.
• students will need a calculator for some simple calculations.

unit 1: nature of astronomy, the night sky, history of astronomy
topics and key terms

• nature of scientific inquiry
• types of astronomical observations
• light - years, au, parsec, astronomical scales
• constellations, celestial sphere
• daily vs annual motion
• historical models (geocentric vs heliocentric)
• eratosthenes, ptolemy, copernicus, brahe, kepler, galileo, newton, hubble
• scientific revolution in astronomy

questions:

1. explain why astronomy relies heavily on indirect evidence and give one example of an observation that cannot be reproduced in a lab.
2. compare the usefulness of au, light - year, and parsecs by describing a situation where each is the most appropriate unit.
3. describe why constellations appear to shift gradually throughout the year, and identify the motion responsible.
4. what is the celestial equator, and how does it relate to earth’s actual equator?
5. explain why stars near the celestial poles appear to move in circles while stars near the celestial equator rise and set.

Explanation:

1. Astronomy relies on indirect evidence because nearly all astronomical objects are inaccessible to in-situ sampling or lab experiments, as they are light-years away. An example is observing the merger of two distant black holes via gravitational waves, which cannot be replicated in a lab setting.
2. 1. AU (Astronomical Unit): Best for distances within our solar system, like describing the distance between Earth and Mars.
3. Light-year: Ideal for interstellar distances, such as the distance between the Sun and the nearest star Proxima Centauri.
4. Parsec: Preferred by professional astronomers for large interstellar/galactic distances when calculating stellar parallax and mapping galactic scales.
5. Constellations shift over the year because of Earth's orbital revolution around the Sun. As Earth moves along its orbit, our line of sight to distant stars changes, making different constellations visible at night across seasons.
6. The celestial equator is an imaginary line on the celestial sphere that is the projection of Earth's equator outwards into space. It divides the celestial sphere into the northern and southern celestial hemispheres, directly aligned with Earth's equator.
7. Stars near celestial poles appear to circle the poles because they are close to the axis of Earth's rotation, so their apparent motion is a small circular path around the pole. Stars near the celestial equator rise and set because Earth's rotation carries our line of sight past them as the planet spins, causing them to move across the full visible sky each day.

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Answer:

1. Astronomy uses indirect evidence as cosmic objects are unreachable; black hole gravitational wave observation cannot be lab-replicated.
2. AU for solar system distances, light-year for interstellar distances, parsec for professional galactic/stellar parallax measurements.
3. Earth's orbital revolution causes the annual constellation shift.
4. The celestial equator is Earth's equator projected onto the celestial sphere, matching its alignment.
5. Polar stars circle due to proximity to Earth's rotation axis; equatorial stars rise/set as Earth spins past them.