Looking Upward

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Lecture 1: Looking Upward — Astronomy 101 with Dr. Brian Keating

Lecture 1 Looking Upward — Astronomy 101 with DrDownload

🌌 Course Introduction

  • Goal: Lay the foundation for a deep understanding of astronomy, the oldest and most accessible science
  • Instructor: Dr. Brian Keating, cosmologist and lifelong lover of astronomy since age 12
  • Course Structure: 8 lectures, covering everything from the solar system to the beginning of time

🌠 Definitions and Clarifications

  • Astronomy: Greek origin “astron” (star) + “nomos” (law) = “star law” or “star culture”
  • Cosmology: Study of the universe at its largest scales (“cosmos” meaning beauty, order)
  • Astrology ≠ Astronomy: Astrology is not falsifiable, not scientific; astronomy is testable and falsifiable

🧠 Why Astronomy Matters

  • Accessible to all: All you need are your eyes
  • Interdisciplinary: Connects physics, philosophy, theology, and history
  • Profound: Invites reflection on existence, time, and human purpose

🧒 Personal Origin Story

  • Age 12: First sight of Jupiter near the Moon sparked his obsession
  • First job to buy a telescope: Venice Deli, Dobbs Ferry, NY
  • First observations: Moon craters, moons of Jupiter — just like Galileo

📖 History & Heroes

🧑‍🎓 Galileo Galilei

  • First to use telescope for astronomy
  • Saw craters on the Moon, moons orbiting Jupiter
  • Used scientific method: observation, theory, repeat
  • Wrong about some things (e.g., cause of tides)

🧠 Other Pioneers

  • Aristotle: Earth is spherical (right), women have fewer teeth (wrong)
  • Eratosthenes: Measured Earth’s circumference with 12% accuracy
  • Copernicus: Proposed heliocentric (Sun-centered) model
  • Kepler: Laws of planetary motion, but made odd conjectures
  • Tycho Brahe: Observed comets outside Earth’s atmosphere, lost nose
  • Giordano Bruno: Proposed infinite worlds, burned at stake
  • Caroline Herschel: First paid female astronomer
  • Cecilia Payne-Gaposchkin: Discovered stars are mostly hydrogen

🌌 Ancient Astronomy

  • Prehistoric Astronomers:
  • Tracked Moon, Sun, constellations
  • Built monuments (e.g., Stonehenge) aligned with celestial events
  • Babylonians/Persians:
  • Developed constellations and zodiac
  • Used astronomy for calendars, commerce, and religion
  • Egyptians & Hebrews:
  • Sun worship, lunar calendars
  • Biblical references to cosmology (“In the beginning…”)

🪐 Terms & Tools

  • Zodiac: The 12 constellations the Sun passes through yearly
  • Planet: From Greek “planētēs” = wanderer
  • Sextant, astrolabe, orrery: Ancient tools to map the heavens

🧪 What Makes Astronomy Scientific?

  • Falsifiability: The hallmark of science
  • Example: Astrology isn’t falsifiable — everything is always true
  • Experimentation Limits:
  • We cannot manipulate the cosmos, only observe it
  • Main data sources: light (electromagnetic radiation), meteoritic material, gravitational waves & neutrinos

🔭 Tools of Observation

  • The Eye: Only organ with brain tissue outside the skull
  • Telescopes: From Galileo’s time to the James Webb Space Telescope
  • Amateur Astronomers: Still contribute to major discoveries

🌍 Shape of the Earth

  • Aristotle & eclipses: Earth’s shadow proves it’s round
  • Eratosthenes: Measured Earth’s circumference using shadows in Alexandria and Syene
  • Earth is an oblate spheroid, not a perfect sphere

⏳ Importance of Timekeeping

  • Accurate calendars crucial for planting, religious observance
  • Timekeeping enabled trade and navigation
  • Greenwich: Prime Meridian origin of universal time

💫 Renaissance Shift

  • Copernicus: Proposed heliocentric model (Sun at center)
  • Retrograde Motion:
  • Explained more simply with heliocentrism
  • Planets appear to reverse direction due to Earth’s relative motion
  • Ptolemaic System: Earth-centered; complex epicycles

🛰️ Space Exploration

  • Moon landing: 1969
  • Mars & Venus probes: Confirm planetary details
  • Olympus Mons (Mars): Tallest volcano in solar system
  • Venera Probes (Venus): Melted in 15 minutes due to heat
  • Kepler Telescope: Found over 2,600 exoplanets

💡 Final Thoughts

  • Science is iterative: We are always refining ideas
  • Humility is key: Great scientists were often wrong
  • Astronomy is for everyone: Inspires awe, wonder, and discovery

“You can’t do astronomy if you’re afraid to be embarrassed by later discoveries.” — Dr. Brian Keating

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