Download Introduction Cosmology Cosmetics Cosmetology ..Greek words

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Transcript
Introduction
Cosmology
Cosmetics
Cosmetology
..Greek words, kosmos, meaning “order,” “harmony,” and
“the world,” and logos, signifying “word” or “discourse”.
(Enc. Britannica)
Cosmology is the study of the origin and evolution of
the Universe
Everything?
Scientific Cosmology attempts to account for the origin
and evolution of the Universe on the basis of laws of
Physics.
Large scale (galaxies) and small scale (elementary
particles, e.g., electrons)
Large scale => gravity
Small scale => laws of quantum mechanics
What is “scientific”?
The description uses models
What is there to describe?
Main features
Stars, Galaxies, blackholes etc. (large scale)
Protons, electrons etc. (small scale)
The in-between are “details”
What is and what is not Science?
A scientific theory is acceptable if:
it can explain all relevant existing observations
it can correctly predict observable phenomena
Thus, a scientific theory inherently includes ways to
verify/falsify itself.
Example:
Lightning occurs when Zeus throws his thunderbolts.
Is it a scientific explanation?
Why not?
Describing our neighborhood
Moon
Planets (Jupiter, Mars, Saturn etc) and Satellites
Sun
Asteroids
Comets
Kuiper belt
Oort cloud
THAT’S THE SOLAR SYSTEM (1 star only, the Sun)
Distances of objects in the Solar system
Earth to Moon:
0.4 million km
(0.4 x 106 km)
Sun to Mercury:
58 x 106 km
Earth to Sun:
150 x 106 km
New unit of distance
(1 AU = Astronomical Unit)
1 AU = 150 x 10 6 km
Earth to Sun:
1 AU
Sun to Mercury:
0.38 AU
Sun to distant Comets:
15 trillion km, or
100,000 AU
Objects beyond the Solar System
Stars
Blackholes
Galaxies
Nebulas etc, etc
Distances of objects beyond the Solar System
Our distance to Nearest Star 260,000 AU
Unit of distance for objects beyond the Solar System
Light year (ly) 9.5x1012 km
Nearest Star is Proxima Centauri 4.23 ly
Sirius (brightest star) 8.6 ly
Deneb 3,000 ly
Milky Way (visible stars)
Galaxies
Local Group
Clusters and Super Clusters of Galaxies