General Astronomy ASTR 1 & 2 – Comprehensive Study Notes (from Transcript)

Course Information

• General Astronomy ASTR 1 & 2, Professor: Keaton Bell

• Schedule: MW 5:05 - 6:20 PM

• Location: CUNY Queens College, Science Building C201

Textbook & Study Resources

• No-cost OpenStax textbook

• Appendix A: “How to Study for an Introductory Astronomy Class”

• Link: https://openstax.org/details/books/astronomy-2e

• Guidance: Follow these recommendations throughout the semester

Student Information (Fill-In)

• Printed Name

• ID #

• Date

• 1.

• 2.

• 3.

• Signature

First Astronomy Night & Observing Assignment

• First Astronomy Night of the semester: Next Wednesday, Sept 3rd from 8:30-9:30 PM

• Weather permitting; cancellations will be announced on BrightSpace

• Complete your Observing Assignment early in the semester! (10% of ASTR 1 grade)

• Presented by QC Society of Physics Students (Instagram: @qc_sps)

Appendix: Study Recommendations

1. Make time to study.

2. Be engaged and undistracted in class.

3. Take careful notes.

4. Read and re-read (before and after lecture).

5. Form a study group.

6. Outline your understanding before quizzes.

7. Explore online resources.

8. Consider the questions at the end of the chapters.

9. Ask questions (in lecture and office hours).

10. Try to get enough sleep.

11. Don’t be too hard on yourself!

What is Science?

• A method for improving our understanding of nature.

• Key components:

  • OBSERVATION / EXPERIMENT

  • Inductive Reasoning

  • Generalizations

  • Predictions

  • Deductive Reasoning

  • PARADIGM/THEORY

What is Not Science? (Science vs Pseudoscience)

• Example concept: a horoscope is not science

• Scientific theories must have testable hypotheses that hold up to repeated experiment

• Pseudoscience: presents as scientific but is not testable or does not withstand experimentation

• Examples of pseudoscience listed: astrology, flat Earth, climate change denial

The Field of Science and Fundamental Forces

• The field of science that addresses the fundamental nature of matter and its interactions

• Four fundamental forces of nature:

  1. Gravity

  2. Electromagnetism

  3. Weak nuclear force

  4. Strong nuclear force

• What is Physics? Physics applied to understanding the universe around us

The Scope of Physics and Astronomy (What We Will Consider)

• In this class, consider from nearest to farthest:

  • Solar System (Sun and Planets)

  • Other Stars

  • Our Galaxy

  • Other Galaxies

  • Universe and Cosmology

Observational Astronomy: What Makes It Unique

• Largely limited to what we can see: light that we collect with telescopes

• Example reference: ESA’s Paranal Observatory

• Note: There are some exceptions to the limitations described

The Scale of Things: Quick Quantitative Facts

• Moon diameter: $D_{ ext{Moon}} = 2{,}159.1 ext{ miles}$

• Moon distance: $d_{ ext{Moon}} = 238{,}900 ext{ miles}$

• Sun diameter: $D_{ ext{Sun}} = 865{,}370 ext{ miles}$

• Sun distance: $d_{ ext{Sun}} = 91{,}550{,}000 ext{ miles}$

• Speed of light: $c = 6.70 imes 10^{8} rac{ ext{miles}}{ ext{hour}}$

Scale Models: Vision through Scaled Representations

• Concept: Scale models shrink everything to an easier-to-visualize size

• NYC Panorama at the Queens Museum as an example: scale 1:1200

  • 1 inch in the model represents 1200 inches (100 feet) in the real city

  • Empire State Building height in model: 15 inches

  • Statue of Liberty height in model: 1 7/8 inches (approximately 1.875 inches)

Scale Models: Lengths, Distances, and Time with Light

• 1 light year definition: the distance light travels in one year at speed $c ext{ (approximately } 2.998 imes 10^{8} frac{m}{s})$

• In this context: 1 light year ≈ $5.8 imes 10^{12} ext{ miles}$

• Question example: How far does light travel in a nanosecond? ~ 1 foot (≈ 0.3048 m)

• Grace Hopper reference: handed out “nanoseconds” to explain computation limits

Scale Models: Earths, Moons, and Nearby Stars

• Earth as an orange; Moon as a grape; 7 feet away at scale factor $1:180{,}000{,}000$

• Real Moon distance: $d_{ ext{Moon}} = 238{,}900 ext{ miles} \ ext{corresponds to} \ 1.3 ext{ light-seconds}$

Scale Models: The Sun-Earth System and Nearby Stars

• Sun as an orange; Earth as a grain of sand; 27 feet away at scale $1:20{,}000{,}000{,}000$

• Next nearest star would be an orange in Houston at this scale

• Are collisions between stars common? No; represented as: 8 light-minutes = 4 light-years (for context)

• Conclusion: NO

Light-Year Scale and Associated Resources

• One light-year: $1 ext{ ly} = 5.8 imes 10^{12} ext{ miles}$

• Video resource: https://www.youtube.com/watch?v=MX3PIkbTQwQ

Galaxy Scale: Notecards and Cosmic Distances

• Scale Models: Galaxy is a notecard; next galaxy is a notecard in the other hand

• Are collisions between galaxies common? Yes in a relative sense; approximately ~100 billion stars per galaxy can be involved in interactions

The Mice: Interacting Galaxies NGC 4676

• Observed as an interacting galaxy pair

• Observational data source: Hubble Space Telescope, Advanced Camera for Surveys

• Credits include: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M. Clampin (STScI/), G. Hartig (STScI), the ACS Science Team and ESA

• Reference designation: STScI-PRC02-11d

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Additional Resources and Video Links

• YouTube resource: https://www.youtube.com/watch?v=D-OGaBQ494E

• YouTube resource (second link): https://www.youtube.com/watch?v=MX3PIkbTQwQ

Connections, Implications, and Practical Takeaways

• Scientific method emphasizes testable hypotheses and repeatable experiments; distinguishes science from pseudoscience

• Understanding scale and distance in astronomy helps contextualize observational limits and the vastness of the Universe

• Observing nights and assignments are integral to hands-on learning and demonstrating practical application of concepts

• Ethical/philosophical note: critical thinking about claims (e.g., pseudoscience) is essential in evaluating real-world phenomena

• Practical implication: use scale models to build intuition for astronomical distances; recognize that real cosmic distances are often incomprehensibly large