The Renaissance in Astronomy

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The Renaissance in Astronomy

• Dr. Mike Reynolds

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Leading Up to the AstroRenaissance

• Astronomy (and yes, astrology!) were considered
  major sciences
• Timekeeping importance to agriculture
• Navigation no MapQuest was available!
• Understanding Events Around Us what did
  astronomical events like eclipses, comets, meteor
  showers mean to people?
• Lets take a quick tour of some of the early
  astronomy its important to hear a little about
  the starting points for astronomy!

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Early Astronomy

• As one of the oldest sciences, if not the oldest,
  early astronomy was important in the day-to-day
  lives of people
• Calendars important due to agriculture seasons
  and time
• Oldest Calendar found to date is 4800 BC from the
  Egypt-Sudan border
• Some African Calendars had the ability to predict
  lunar phases
• Navigation
• Simple Human Curiosity

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SoWhat Time Is It?

• During the day
• People observed the Suns path
• Shadows pre-sundials
• During the night
• Moons position and phase
• Star positions
• During the Year
• Suns seasonal position

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Why a 24-Hour Day?

• Why not break the day into 10 segments? Or
  1,000,000?
• Blame the Sumerians, over 4000 years ago
• They used their fingers with 3 division each to
  count thumb as a counter
• The Sumerians divided the day into 12 units (2
  hands) and night into 12 units
• Ancient Babylonians inherited 24 hour days and
  presumably added their base 60 counting system
• hours into 60 minutes, minutes into 60 seconds

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Calendars Based on the Moon

• Lunar calendars have periods of 29 or 30 days
• The Month Moonth!
• Some examples of Calendars based on the Moon
• Metonic and Jewish 19 year periods
• Jewish Passover, thus New Testament Easter is
  also based on this calendar
• Saros eclipse cycles of 18 years
• Mayan 260 days based on eclipse seasons

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Other Observations?

• Ancient Civilizations observed positions of
  specific stars and the planets
• Rising and setting times
• ?Often ancient observatories were built to
  accomplish this fairly accurately
• The Mayan observatory at Chichén Itzá had windows
  strategically placed for observations of Venus

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More Ancient Observations

• Polynesians were some of the best observers
• island-to-island sailing navigation
• Chinese incredibly-detailed observations
• For the Emperor son of the heavens
• Accurately predict events to show divineness
• First recorded observations comets, meteor
  showers, meteorites, eclipse predictions,
  supernovae
• Built instruments to conduct these studies

A Traditional Polynesian Navigational Instrument
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More Ancient Observations

• Mesopotamia First comprehensive catalog of the
  night sky around 750 BC
• Babylonians practice of astrology and astronomy
• Egyptians infatuation with the heavens
• First Recorded Sundials ? Obelisks
• 3500 BC seasons, day clock
• Pyramids
• 2680 BC Great Pyramid at Giza completed

Obelisk Karnak Temple
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Jewish and Christian Traditions

• The Bibles Old and New Testaments contain
  numerous astronomical references
• The Jewish Bible, or Old Testament, refers to
  stars, constellations, eclipses
• The Christian New Testament also has several
  astronomical references
• Example the Star of Bethlehem, denoting the
  birth of Jesus

Adoration of The Magi Giotto 1267-1337
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Ancient Greek and Islamic Astronomy and Science
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The Greeks
Farnese Atlas 2nd Century AD Believed to be based
on Hipparchus

• Credited with development of scientific
  principles, starting around 500 BC
• Alexandria, Egypt was a great library and
  research center that opened around 300 BC
• Eratosthenes determined Earths circumference by
  measuring the Suns shadow at two points on Earth
  around 240 BC
• Hipparchus developed a stellar brightness
  magnitude scale
• Ptolemy Geocentric Model of the Universe
  (100-170 AD)

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Islamic Contributions

• 8th and 9th Centuries AD
• Kept and translated historical records
• Developed Algebra
• New instruments and techniques
• Developed many constellation star names
• Examples Aldebaran, Algol (Al the)
• The researchers were not only Muslims, included
  Jews and Christians worked with Hindus

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Total Solar Eclipses

• Over time, people have been profoundly affected
  by a total solar eclipse
• St. Benedict 480-547 AD
• A total solar eclipse so impacted him that he
  started his still-famous work the Benedictine
  Society

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Total Solar Eclipses simply the most-spectacular
astronomical event (in my humble opinion)
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The Next Major Advances Brings Us to the
Renaissance!
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The Copernican Revolution!

• This Revolution was based on the works of four
  men Copernicus, Brahe, Kepler, and Galileo
• Nicolaus Copernicus, a Polish astronomer,
  believed there were too many errors in the
  Ptolemaic Geocentric Universe
• Ptolemys retrograde was too complicated
• So Copernicus developed a Sun-Centered Solar
  System Heliocentric

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Copernicus

• Studied math and optics in college as well as
  Canon (Church) Law
• His work was released late because he was a
  perfectionist
• For relaxation he painted and translated Greek
  poetry into Latin!

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Observations of Motion

• Tycho Brahe made extensive measurements of
  astronomical objects until his death in 1601
• These measurements were accurate to better than
  1/100 of a degree!
• Tychos assistant was Johannes Kepler
• Kepler tried to get Tychos data to fit the
  Copernican Heliocentric Solar System Model
• Data did not exactly work for a Heliocentric
  Solar System! So Kepler looked for a new model

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Tycho the Man

• Lost his nose in a sword fight!
• Replaced it with a silver beak
• Rumored he died of bladder complications
• Refused to go out of courtesy after a long
  wine-drinking bout but couldnt go later!

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And what about Johannes?

• Rumor is that Tycho really didnt like Kepler
• Keplers mother was once charged with witchcraft
  Kepler successfully defended her
• Keplers worst subject in college?
• Astronomy!

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Keplers Laws

• Remember Keplers difficulties fitting Tychos
  data to the Heliocentric Solar System?
• Kepler found the orbits of the planets were not
  circles, leading to three Laws
• Keplers 1st Law the paths of the planets around
  the Sun are ellipses, with the Sun at one focus
• Keplers 2nd Law A planet moves so that its
  radius vector sweeps out equal areas in equal
  times

Foci
Circular Orbit
Elliptical Orbit
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Time A
Area A
Area B
Time B
Area A Area B
Time A Time B
Perihelion Closest point to the Sun Aphelion
Farthest point from the Sun
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Keplers Laws

• Keplers 3rd Law The ratio between the square of
  the time needed by a planet to make a revolution
  around the Sun and the cube of its average
  distance from the Sun is the same for all of the
  planets
• (Period of planet)2
• (Average Orbit Radius)3

same for all planets
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Galileo Galilei

• First used the telescope astronomically in 1609
• Sunspots blemishes on the Sun
• Saw features on the Moon
• Mare Italian for sea or body of water
• Mercury and Venus showed phases
• This meant Mercury and Venus orbits the Sun
  between Earth and the Sun!
• Jupiter had four moons
• Hard to have moons in a Ptolemaic system!
• Saturn had ears
• Milky Way had countless stars

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Before The Telescope
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Early Telescopes
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The First Telescope?

• Jan (or Han) Lippershey of Holland is given
  credit for inventing the first telescope in 1608
  a refracting telescope
• Lippershey was a spectacle maker
• He called it Kijker, meaning "looker" in Dutch
• Lippershey unsuccessfully tried to patent the
  telescope, as well as telescope binoculars
• Lippershey thought the telescopes best use was
  military

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So if not Lippershey

• Some argue that Lippershey stole the idea from
  Hans and Zacharias Janssen, another pair of
  spectacle makers, who supposedly assembled the
  telescope around 1595
• Rumor has it Lippersheys son actually discovered
  the right lens combination!
• He put together two lenses and spied the local
  church steeple!

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Galileos Optik Sticks
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Porta Telescope Drawing, 1609
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Early Telescopes

• Hevelius Aerial Telescope

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The Mathematical Finish!
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Sir Isaac Newton

• In addition to his Laws, he is responsible for
• Newtonian reflector telescope
• Prism / spectrum
• Binomial theorem of Algebra
• Invented Calculus!
• All before the age of 23

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Newtons 1st Law of Motion

• An object remains at rest or in motion at a
  constant velocity unless acted upon by an outside
  force

Good is the Force!

• What is a Force?
• Any influence that can change the speed or
  direction of motion of an object

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Newtons 2nd Law of Motion

• A relationship between acceleration of an object,
  force placed on the object, and the objects mass

force (mass) (acceleration)
f ma
Units f kg-m/s-s Newton (N)
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Newtons 3rd Law of Motion

• When one object exerts a force on a second
  object, the second object exerts an equal force
  in the opposite direction on the first object
• Sometimes called the Action Reaction law
• Rocket blasting off action is force of the
  combustion/flame, reaction is the rocket moving
  in the opposite direction of the flame
• A book pushes against a table (a force), the
  table pushes back (opposite and equal force)

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Newtons Universal Law of Gravity

• Every object in the universe attracts every other
  object with a force proportional to both of their
  masses and inversely proportional to the square
  of the distance between them

F Gravitational force
G Gravitational Constant
Gm1m2 R2
F
m1 first objects mass
m2 second objects mass
R distance between the two objects
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