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