Download Lecture 1 - U of L Class Index

The Universe and
our place in it
Our Universe
Address: Earth
• How would the
Universal post office
find us?
Star
A large, glowing ball of gas that generates
heat and light through nuclear fusion
Planet
A moderately large object which orbits a star;
it shines by reflected light. Planets may be
rocky, icy, or gaseous in composition.
Solar system to scale
Giants
Moon
An object which
orbits a planet.
Inferior
planets
Moons
Moons
Asteroid
A relatively small
and rocky object
which orbits a star.
Comet
A relatively
small and
icy object
which orbits
a star.
Comet Halley
Aphelion 30 AU
Orbital period 76 years
Solar (Star) System
A star and all the material which orbits it,
including its planets and moons
Protoplanets
Nebula
An interstellar cloud of gas and/or dust
Galaxy
A great island of stars in space, all
held together by gravity and
orbiting a common center
How large is our Galaxy?
Universe
The sum total of all matter and
energy; that is, everything within
and between all galaxies
Atom
Microscopic “building blocks” of all
chemical elements
From the very big to the very small
How large is the Universe?
• Now let’s view the Universe in terms of meters
– Powers of 10 or 10
?
A Universe in motion
• Contrary to our perception, we are not “sitting
still.”
• We are moving with the Earth.
– and not just in one direction
The Earth rotates
around it’s axis once
every day!
Speed at equator ~
0.5 km s-1
The Earth orbits around
the Sun once every
year!
Speed ~ 30 km s-1
The Earth’s axis is tilted
by 23.5º!
Our Sun moves relative to
the other stars in the local
Solar neighborhood!
Our Sun and the stars of the
local Solar neighborhood orbit
around the center of the Milky
Way Galaxy every 230 million
years!
Speed ~ 220 km s-1
How has the study of astronomy
affected human history?
• Copernican Revolution showed that Earth was not
the center of the universe
• Study of planetary motion led to Newton’s Laws of
motion and gravity
• Newton’s laws laid the foundation of the industrial
revolution
• Modern discoveries are continuing to expand our
“cosmic perspective”
Throughout history, astronomy has provided an
expanded perspective on Earth that has grown hand in
hand with social and technological developments
So how does one get from this, the norm…
… to this the exception?