Exploration of Space:
What are some techniques used to explore space?
Telescopes
Refracting
Radio
Reflecting
Hubble
Space craft
Manned--> Mercury, Apollo, Space shuttle, Skylab, International Space
Station
Unmanned--> Viking, Voyager, Mars-lander
Light and waves
Waves
What is a wave?
What creates waves and how are they generated?
How do waves move?
Types of waves:
Transverse Waves
perpendicular particle displacement and wave propagation.
Longitudinal Waves
wave propagation and particle displacement are in same direction
Water Waves
Particles move both vertical and horizontal—waves propagate horizontally
Parts of a wave
Wavelength (l)
one complete wave—trough & crests
period (T)
time it takes for one l to pass a given point.
frequency (f)
number of oscillations per unit time. (f=1/T)
speed (velocity) (v)
v = l/T = lf
As a wave travels through a medium, what is the net motion of the particles the energy is
passing through?
Waves transport energy through a medium—it does not transport the mass.
Wave in a baseball stadium
Wheat field in the wind
Doppler Effect: What is it?
Fire truck goes by with siren.
What does it sound like far away? Close up?
Why does it change?
Electromagnetic Radiation
What is electromagnetic radiation?
Human eye is capable of seeing only a small portion of this spectrum—
This visible spectrum is known as white light but can be broken down into
components of differing .l
Violet most energy shortest l
Blue
Green
Yellow
Orange
Red least energy longest l
Changing the wavelength--> changes the color
Changing the energy--> changes the color
How can this spectrum be affected by different physical conditions (pressure, temperature, obstructions)?
Continuous spectrum
Hot or incandescent medium generating energy under a high pressure
Bright line spectrum
Hot gas under low pressure
Colored lines on a black background
Dark line spectrum
White light through cool gas under low pressure
Gas absorbs certain l based on composition of gas. Creates dark lines in spectrum
Remote sensing
Telescopes
visual description
relative motion
Color
says something about energy
Spectrum
says something about composition
How does doppler effect fit into this and how can it help us understand the universe?
Combine spectra and Doppler effect
determines how earth is moving relative to other bodies.
Red shift and blue shift?
A wave has a wavelength of 0.2 meters and has a period of 30 seconds.
A) What is the velocity of the wave?
B) what is the frequency of the wave
A wave has a velocity of 0.00723 m/sec and a frequency of 0.05 hz.
a) what is the period of the wave
b) what is the wavelength of the wave
f = 1/T
v = l/T = lf
How are stars created?
Interstellar clouds contract
protostar
increase in temp over time
hydrostatic equilibrium--> stable star
Life span of stable star depends on mass and energy
blue stars--> few million years
red stars--> hundreds of billions years
yellow stars--> ~ 10 billion years
Where is our sun in its life cycle?
When a star dies it often forms a red giant
Red Giants
no reaction in core--> no pressure--> core contracts --> creates heat
outward layers of star expand and cool--> creates red appearance
Low mass stars
white dwarf
Hydrogen burns out
Medium mass stars
Red giant forms
core continues to collapse and heat
helium --> carbon
collapses into white dwarf with gas cloud
planetary nebulae
Our Sun
Medium sized star
surface ~10,000oF
gravity =27.5x that on earth
Equator and poles rotate at different rates
25 days at equator and 28 days at middle latitudes
magnetic field reverses every 22 years (more in a bit)
interior is gas not solid
~73% Hydrogen and 25% helium
Made up of four parts
solar interior
visible surface (photosphere)
chromosphere
corona
Solar interior
Nuclear fusion reaction generates energy
conversion of 4 H atoms to He atoms creates energy (mass difference between
elements)
temperature to initiate this reaction is several million degrees
Sun has expected life span of 10 billion years
Photosphere
sun’s surface
granulation
created by convection
sunspots
cool spots on surface
regions of strong magnetism
occur in pairs with opposite polarity
regions of most violent solar activity
Chromosphere
Thin layer of incandescent gas
mostly hydrogen
flamelike structures (spicules)
Corona
envelope of ionized gasses (top of atmosphere)
extends a million km from sun
at edge of envelope--> gasses escape gravity
solar wind
photons
Other features of the sun:
Prominences
Solar Flares