Download Week one: Space Physics and Aeronomy (pdf, 1.3 MB)

Space Physics and Aeronomy
Lecture 1: Our little corner in the Universe + physics concepts
Lecture 2: The Sun
Lecture 3: The Magnetosphere and the Ionosphere
Lecture 4: Space Weather and Aurora
Lecture 1:
Our little corner in the Universe
+ physics concepts
Waves
λ
Mechanical Waves
Electromagnetic Waves
-
Propagate through empty space
Time varying electric field produces magnetic field
(Ampere's law)
Time varying magnetic field produces electric field
(Faraday’s law)
-
-
λ
C=3*108 m/s
+
• Energy
• Momentum
Sources of EM radiation
Do colors exist?
Λ=400 nm
Λ=700 nm
Sources of visible light
White
Visible light
0.000000000000000000000003%
Doppler Effect
Doppler Effect
“Spread out”
waves
Red-shifted
Compressed
waves:
Blue-shifted
Doppler shift
Red shift of galaxies
Edwin Hubble recognized
the red shift as a Doppler
effect.
• He concluded that
galaxies were moving
away at great speed.
• No galaxies were found
heading toward Earth.
Hubble deduced that the
whole Universe must
be expanding
History of the Universe
Kennedy Space Center, April 20, 2001
History of the Universe
Cosmic microwave background
The oldest light in the Universe
• White hot fog of H plasma
• The Wilkinson Microwave Anisotropy Probe
Atoms and molecules combined into
gaseous nebulae.
Gravity caused collapse of
gaseous nebulae.
Collapse resulted in increases in:



Temperature.
Density.
Rate of rotation
Birth of the First Stars
Mass in nebulae was not equally distributed.
An initially more massive region began to pull in gas.
 This region gained mass and density.
 Mass compacted into a smaller region and began to
rotate.
Rotation rate increased, developing a disk shape.
 The central ball of the disk became hot enough to
glow.
 A protostar is born.

Birth of the First Stars
The protostar continued to grow,
 pulling in more mass and creating a denser core.
 Temperatures soared to 10 million degrees.
 At these temps, hydrogen nuclei fused to create
helium.
 With the start of nuclear fusion, the protostar
“ignited.”
Gigantic power generator
Pressure
H
H
H
H
Energy
T=15000000°C
He
The energy is created
deep inside the core.
H, He, Li, Be, B
Nebulae from which first-generation stars formed
consisted entirely of light elements.
These first-generation stars exhausted H2 fuel rapidly.
• As the stars became H2-starved, they initiated:
• Collapse and heating.
• Catastrophic supernova.
Where do elements come from?
• Stellar nucleosynthesis
• Stars are “element factories.”
Where do elements come from?
• First-generation stars left a legacy of heavier elements.
• Second-generation stars repeated heavy element
genesis.
• Succeeding generations contain more heavy elements.
• The sun may be a 3rt, 4th, or 5th-generation star.
The mix of elements found on Earth include:
• Primordial gas from the Big Bang.
• The disgorged contents of exploded stars.
We really ARE all made out of stardust!
Where do elements come from?
Solar System Formation
• The ball at the center grows dense and hot.
• Fusion reactions begin; the sun is born.
• Dust in the rings condenses into particles.
• Particles coalesce to form planetesimals.
Earth Formation
• Planetesimals clump into a lumpy protoplanet.
• The interior heats, softens, and forms a sphere.
The interior differentiates into:

A central iron-rich core, and

A stony outer shell—a mantle.
Formation of the Moon
• Mars-sized protoplanet collides with Earth.
• The planet and a part of Earth’s mantle are disintegrated.
• Collision debris forms a ring around Earth.
• The debris coalesces and forms the moon.
• The moon has a composition similar to Earth’s mantle.
The Atmosphere and Oceans
• The atmosphere develops from volcanic gases.
• When Earth becomes cool enough:
• Moisture condenses and accumulates.
• The oceans come into existence.
Dynamo
S
• The motion of an
electric charge
produces a magnetic
field
• Earth’s magnetic field is
like a giant dipole bar
magnet
• The field weaken with
distance
N
Plasma
• It is a forth fundamental state of mater.
• Plasma is a gas of ionized atoms (or molecules). Plasma
acts like a fluid and it is affected by electric and magnetic
forces.
3 fundamental states of matter
Where can we see plasma on Earth?
Neon Light
Lightning
Laboratory
Our little corner of the Universe
The Sun makes up
99.8%
about
of all of the mass in our solar system
You are here!
Our little corner of the Universe
Neutral Atmosphere
~ 100 km
human activity
(including air traffic)
~ 15 km
PLASMA