ET

  • Stellar astronomy 

    • the study of the objects that lie beyond the solar system and the processes by which these objects interact with one another

  • Scientific Method

    • Ask a “simple” question
    • Research the question
    • Formulate a Hypothesis (An educated guess, not a theory)
    • Test your hypothesis (design an experiment)
    • Analyze your data and develop a “theory” (based on facts, evidence)
    • Must be subject to peer review 

  • Critical Thinking

    • Exploring misinformation and disinformation 
    • Extraordinary claims require Extraordinary evidence 
    • All things considered; the simplest explanation is usually the best 
    • Humans have always been terrible at understanding coincidences
    • What is your evidence? What is your source?
    • How reliable is that source? Who decides its reliability?
    • There are NO alternative facts
    • Science has always been a “work in progress”

  • The Roots of Astronomy 

    • The ancients required knowledge of the sky in order to survive
    • They used the sky:
    • As a calendar (seasons)
    • For navigation
    • For story telling
    • And then there was Curiosity
    • Most early civilizations used lunar cycles as their calendars

  • Why was understanding the sky so important for survival?

    • When to plant their crops, when to harvest
    • When herds were migrating
    • When they should migrate
    • When was it safe to travel into the mountains for hunting and gathering?
    • Understanding the timing of ocean tides for fish and travel

  • Determined Seasons using the sun 

    • Stonehenge: Summer solstice
    • Newgrange: Winter solstice
    • Chichen Itza: Equinoxes

  • Determined seasons using the stars

    • Summer and spring have different star systems

  • Navigation

    • Used Polaris as a “North, South Landmark
    • Minoans used Hydra as their “West, East Landmark”

  • Curiosity 

    • What were the wanderers? What were meteors? What were comets? Why did the moon change shape? What were eclipses?

  • Most common problems Astronomers face

    • We cannot touch what we are studying
    • The only thing we can study is its light
    • Enormous distances
    • Difficult to measure distances accurately. Without distance, there are many properties we can't understand 
    • Enormous sizes/masses/densities/speeds
    • Requires “new” physics, Special and general Relativity, Particle Physics and more 
    • Time (millions and billions of years)
    • Difficult to reconstruct histories, can only be determined by studying “populations” of objects 

  • Spectroscopy 

    • The study of an object’s light
    • Wavelength, absorption lines, hydrogen, sodium, calcium etc

  • Ground based telescopes 

  • Space telescopes

  • James Webb telescope (JWST)

  • Laboratory research

  • Measuring distances in astronomy

    • One astronomical unit (AU) is 93 million miles, average distance from the earth to the sun
    • One light year (LY)  is the distance light travels in one year
    • One parsec (PC) is 3.26 light years
    • At 65 Mph it would take 163 years to drive to the sun, 1AU
    • 100,000

  • Light travel units (LTU)

    • Speed of light is 186,000 miles a second or 300,000 km a second
    • Light second is the distance light travels in one second
    • Moon is 1.3 light seconds away
    • Light minute is the distance light travels in one minute 
    • The sun is 8.3 light minutes away
    • Light hour, light day, light year etc

  • How far can you see without telescopes (naked eye)

    • The farthest planet you can see is Uranus, 2 hours 40 light minutes
    • The farthest star you can see is 16,000 ly in Cassiopeia 
    • The farthest object you can see naked eye is the Andromeda Galaxy, 4.3 million ly

  • Where are we?

    • Earth in Sol’s system, located in the solar neighborhood, high is a group of stars located in the Milky Way galaxy

    • Diameter: 140,000 light years across 

    • Around 1.5 trillion masses (100-400 billion stars)

    • The sun is located around 30,000 ly from the center of the galaxy 

    • Milky Way is located in the “local group” of galaxies

    • Approximately 80 galaxies

    • The area between galaxies is called “intergalactic space”

    • Galaxy groups are organized into galaxy clusters

    • Our local group is located in the Virgo cluster 

    • Clusters are organized into superclusters 

    • The Virgo cluster is located in the Virgo supercluster (laniakea)

    • Superclusters are organized into filaments and walls 

    • Visible universes

    • 5% of the universe is made out of visible matter 

    • 27% is made out of dark matter

    • 68% is made out of dark energy

      Deep Sky Objects
      The Constellations
      Areas of the sky
      Pareidolia
      Illusion of. Recognizable image where none exists
      The face on the surface features of the moon
      Asterism
      An asterism is a recognizable pattern of stars
      Big Dipper, Little Dipper, Orion
      The classical constellations
      48 classical constellations were described by Ptolemy in “Almagest” which was written in 120 AD
      Pallets of marker-3200 BC
      The oldest known constellations
      Bayer Catalogue: southern sky
      Some defunct constellations… Felis (the cat) noctura (the owl)
      Using constellations
      Mnemonics
      Navigational aids
      Art
      Rituals and calendars
      As storytelling mnemonics
      The story of Perseus and Andromeda
      Navigation
      Urea Major: the Drinking Gourd- Polaris is North
      Art
      Altas- Palace of Farnese, Rome
      Starry Night- Van Gogh
      Astronomical Alignments
      Lakota Medicine Wheel
      Mayan Celestial Alignments
      Modern Constellations
      A constellation is an area of the sky
      The sky is divided into 88 official constellations. Most are based upon the constellations of the Ancient Greek tradition and contains the signs of the zodiac
      The 13 constellations of the Zodiac are called the Zodiacal Constellations
      Star names
      Individual stars can have many names
      Naming the stars
      Star names and designations
      Proper names
      Bayer designations
      Flamsteed designations
      Proper names of stars
      Most bright star names are Arabic
      They begin with “Al”, which means “the”
      Algol-the ghoul, Alioth-the black horse, Alkaid-the leader of the recession of mourners, Alnilam-the string of pearls Alnitak-the belt
      Bayer designations
      All stars have other names
      The Bayer designation uses the Greek alphabet to designate the stars. The brightest star is the alpha star, the second brightest is the beta star, etc
      The Greek letter can then be followed by “in” and the constellation name, or the constellation’s genitive (possessive name)
      Example the brightest star in Orion would be (alpha) in Orion
      Alpha, beta, gamma, delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu, nu, xi, omicron, pi, rho, sigma, tau, upsilon, phi, chi, psi, omega
      Flamsteed designation
      Stars can also have a “Flamsteed number”
      25 in Orion; 25 Orionis
      Drake Equation
      N=R*. Fp x ne x fl x fi x fc x L
      N= number of civilizations with which humans could communicate
      R*= mean rate of star formation
      Fp= fraction of stars that have planets
      Ne= mean number of lancets that could support life per star with planets
      Fl= fraction of life supporting planets that develop life
      Fi= fraction of planets with life where life develops intelligence
      Fe= fraction of planets with life where life develops intelligence
      Fe= fraction of intelligent civilizations that develop communication
      L= mean length of time that civilizations can communicate
      Charles Messier 1730-1817 (will be on quiz)
      Comet hunter
      Nicknamed the Comet Ferret
      August 1758, discovery of Messier Object #1
      Commonly called M1
      Galaxies
      The largest entities in the universe
      Huge accumulations from several million to hundreds of trillions of stars
      Nebulae-4 types
      Clouds of dust and gas, remnants of dying or dead stars
      Emission Nebula
      Emits light and glow as newly formed stars ionize the gases
      The red color is caused by the ionization of hydrogen gases
      The “birthplaces” of new stars
      Evolve to become “open clusters”
      Reflection Nebula
      The bluish white light is created as light from newly formed stars is reflected off left over dust grains
      Absorption Nebula
      Also called “dark nebula”, are dust clouds which block light
      Orion Nebula, Horsehead Nebula
      Planetary Nebula
      Ejected envelopes of red giant stars
      Appear as expanding, symmetrical clouds of gas with shapes similar to “smoke rings”
      Supernova Remnants
      Remnants of a massive star, greater than 8 solar masses, which has violently exploded
      The Fate of a Star, whether or out it ends its life as a Planetary Nebula, SuperNova, Neutron Star, Black hole, etc, is determined by its MASS
      M1 The Crab Nebula
      A bright supernova recorded by Chinese and Arab astronomers in 1054
      Located at a distance of about 6.5k light years
      Star Clusters
      Two categories of Clusters
      Globular Clusters
      Ancient stars: 10-12 billion years old as old or older than the galaxies
      Cool “red” stars
      Population 10k-1 million stars
      Separated by light weeks/months
      Found in the “halo” of the galaxy
      Open Clusters
      Also called Galactic Clusters
      Young, newly formed stars… “blue and white” stars
      Population: 10-300 stars
      Found within the plane of the galaxy
      Binary Star Systems
      Star system made up of two gravitationally bound stars
      Messier 40, double star M40 (WNC 4) in Ursa Major
      The celestial sphere
      A rotating crystalline sphere to which the celestial bodies are attached
      The belief that everything revolves around the Earth
      Celestial Equator
      Imaginary line that divides the celestial sphere into Northern and Southern Hemispheres
      Meridian
      Imaginary line that runs from the north to the south and divides the Celestial Sphere into East and West Hemispheres
      North/South Celestial Poles (NCP)-(SCP)
      The north and south celestial poles are the two magi army points in the sky where the Earth’s axis is extended out onto the celestial sphere
      Ecliptic
      Apparent path of the Sun, Moon and planets through the background stars of the Zodiacal constellations