Classification of Things
Dr. Harold Williams
Montgomery College Planetarium
http://Montgomerycollege.edu/Departments/planet/
Who, Why, What, Where,
When, and How
• Who and What are classification questions
• Who and Why are Religious questions
• What, Where, When, and How are
Scientific Questions
• Who, Why, What, Where, When, and How
are Philosophical Questions
• Classification spans both Religion and
Science by asking Who and What!
Some Common Classifications in
Science
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Periodic Table of the Elements
Particle Physics and the Standard Model
Fundamental Interactions of Physics
Electron Orbitals or Probability Distributions, the Auf Bau
Geological Time Scales
Biology and the Tree of Life
Spectral Classification of the Stars
Hertzsprung-Russell Diagram and Luminosity Classes as
well as spectral classifications
• Types of Star Clusters
• Types of Galaxies
Big Bang made 75% H, 25% He – stars make everything else
Fundamental Particles
http://en.wikipedia.org/wiki/Elementary_particles
What are the fundamental
building blocks of matter?
Proton
Neutron
Quarks
Proton
Neutron
• Protons and neutrons are made of quarks
• Up quark (u) has charge +2/3
• Down quark (d) has charge -1/3
Fundamental Forces according to the
Wikipedia
• Electromagnetism
http://en.wikipedia.org/wiki/Electromagnetic_inter
action
• Weak Nuclear Force
http://en.wikipedia.org/wiki/Weak_interactions
• Electroweak
http://en.wikipedia.org/wiki/Electroweak_interacti
on
• Strong Nuclear Force
http://en.wikipedia.org/wiki/Strong_interaction
• Gravity http://en.wikipedia.org/wiki/Gravity
Electrons in Atoms, Auf Bau
• In quantum
mechanics an
electron in an atom
does not orbit in the
usual sense
• We can know only
the probability of
finding an electron at
a particular spot
The Geological Time Scale
Tree of Life
• Mapping genetic
relationships has led
biologists to discover this
new “tree of life.”
• Plants and animals are a
small part of the tree.
• Suggests likely
characteristics of common
ancestor.
Lines in a star’s spectrum correspond to a spectral type that reveals
its temperature http://en.wikipedia.org/wiki/Spectral_type
(Hottest)
O B A F G K M
(Coolest)
Remembering Spectral Types
(Hottest)
O B A F G K M
(Coolest)
• Oh, Be A Fine Girl, Kiss Me
• Oh, Be A Fine Guy, Kiss Me
• Oh, Be A Fine Gay, Kiss Me
• Only Boys Accepting Feminism Get Kissed
Meaningfully
Pioneers of Stellar Classification
• Annie Jump
Cannon and the
“calculators” at
Harvard laid the
foundation of
modern stellar
classification
H-R diagram
depicts:
Temperature
Luminosity
Color
Spectral Type
Luminosity
Radius
Temperature
What are the two types of star
clusters?
Open cluster: A few thousand loosely packed stars
http://en.wikipedia.org/wiki/Open_clusters
Globular cluster: Up to a million or more stars in a dense ball bound
together by gravity http://en.wikipedia.org/wiki/Globular_cluster
What are the three major types of
galaxies?
Hubble
Ultra
Deep
Field
Hubble
Ultra
Deep
Field
Hubble
Ultra
Deep
Field
Spiral Galaxy
Hubble
Ultra
Deep
Field
Spiral Galaxy
Hubble
Ultra
Deep
Field
EllipticalGalaxy
Galaxy
Elliptical
Spiral Galaxy
Hubble
Ultra
Deep
Field
EllipticalGalaxy
Galaxy
Elliptical
Spiral Galaxy
Hubble
Ultra
Deep
Field
EllipticalGalaxy
Galaxy
Elliptical
Irregular Galaxies
Spiral Galaxy
A better name
• Spiral galaxies might be better named by
calling them Disk galaxies!
• Some Disk galaxies have no or little spiral
structure, but they are still have disks.
Spheroid
Dominates
Hubble’s galaxy classes
Disk
Dominates
Categories
• http://en.wikipedia.org/wiki/Categories_%28Arist
otle%29
• Categories By Aristotle Written 350 B.C.E
Translated by E. M. Edghill another one.
• Categories List