Transcript 29.1 Models of the Solar System

Origin of the Universe
Raisin bread analogy of an
expanding universe
Expansion Evidence
 Stars are made of elemental gases that emit
specific wavelengths within the electromagnetic
spectrum based on their chemical composition.
Each gas emits certain wavelengths that are
unique to that element.
 The combination of a star’s elements which
produce a pattern of spectral lines can be used
to identify the star rather like a fingerprint or bar
code.
Electromagnetic Spectrum
Shifting of Wavelengths is called
the Doppler Effect
• Change in the wavelength of
light emitted by an object due
to its motion
• Movement toward “squeezes” the
wavelength
• Shorter wavelength
• Light shifted toward the blue end
of the spectrum
• Movement away stretches the
wavelength
• Longer wavelength
• Light shifted toward the red end
of spectrum
RED SHIFT – BLUE SHIFT
• The greater the degree of shift of the spectral
lines, the faster the object is moving away
• The star light DOES NOT appear red or blue (it
still appears as white light from the star)
• The “bar code” for each element either shifts to
the shorter wavelength blue end of the spectrum
or to the longer wavelength red end of the
spectrum
What is the best
inference that can be
made concerning the
movements of
Galaxies A, B, and
C?
Our solar system is part of the
spiral Milky Way Galaxy
Edge-on view of the
Milk Way Galaxy
Spiral galaxy in the constellation
Andromeda
Nebular Theory
1. The sun and planets
formed from a rotating
disk of dust and gases.
2. As the speed of
rotation increased the
disk flattened out.
3. Matter became
concentrated in the
center where the sun
eventually formed.
OUR SOLAR SYSTEM
Inner Planets
Are referred to as
terrestrial planets
because they consist
mostly of solid rock
and are similar to the
Earth.
OUR SOLAR SYSTEM
Outer Planets
• Are grouped together
because they are large
and gaseous. The are
called “Jovian” planets
because they are similar
to Jupiter.
• They are larger than the
terrestrial planets, have
a much lower density
and are composed of
mostly gases.
Terrestrial Planets – Earth largest
solid, smaller, denser
NO LONGER
CONSIDERED
A PLANET
Earth compared to Jovian Planets
gaseous, large, low density
Models of the Solar System
1. a) Geocentric “Earth Centered” –
Ptolemy believed the Earth was a
sphere that stayed motionless at the
center of the universe
b) Heliocentric “Sun Centered” –
Copernicus believed the Earth and
other planets orbited the sun.
Rotation – spinning of the Earth on it’s
axis (24 hours – day & night)
Revolution – the Earth
orbiting around the sun
(365 days - seasons)
Precession
• Is the slight wobbling of the
Earth’s axis over 26,000 years.
A. Perihelion –
Earth is closest to
the sun (about 147
million km). This
happens on Jan.3rd.
B. Aphelion – Earth
is farthest from the
sun (about 152
million km). This
occurs on July 4th.
Law #1: Law of Ellipses – The path of
each planet around the sun is an ellipse
with the sun at one focus.
1. What is the eccentricity of the ellipse
below?
f1
d=1
f2
L = 10
2. Which planets have an orbit that is less eccentric than
the ellipse above?
3. Which planets have an orbit that is more eccentric than
the ellipse above?
Law #2 Law of Equal Areas
As a planet revolves around its focus points,
it will cover the same area in equal time.
http://www.phy.ntnu.edu.tw/java/Kepler/Kepler.html
Law #3: Law of Periods
The farther a planet is from the sun, the
longer it will take to complete one orbit
(revolution) around the sun.
Solar Activity
Sunspots- cool, dark areas of gas
within the photosphere that are
caused by powerful magnetic fields.
What
color
stars are
hottest?
Coldest?
Red Super
Giants
Red
Giants
White
Dwarfs
COLOR
AND
TEMPERATURE
ARE
RELATED!
Which groups of stars are the BRIGHTEST?
Which group of stars is the HOTTEST?
Which groups of stars are the SMALLEST
and DIMMEST?
Foucault’s Pendulum
Foucault used a large free-swinging
pendulum. Once put into motion a
pendulum will continue swinging in the
same direction unless acted upon by an
outside force. Sharp points on the bottom of
the pendulum made marks in a circular
motion and returned to its starting position
after 24 hours.
2. Foucault’s pendulum proved that the
Earth DOES rotate on an axis.
Horizon and Zenith
Path
of the
Sun
Path
of
the
Sun
Moon Phases
Half of the moon is always receiving light
from the sun.
The “lit” portion that is visible to earth varies
as the moon REVOLVES around earth. THIS
CAUSES THE PHASES OF THE MOON.
Visible portion of moon growing = waxing
Visible portion of moon shrinking = waning
The moon phases are cyclical – they are reoccuring or repeating in the same pattern.
Phases of the Moon
Lunar Phases
Cycle of Lunar Phases
Takes 29.53 days
This is because when moon gets back to
its original position in 27.3 days, the earth
has moved 1°/day or about 27°.
The moon moving at l3°/day takes about 2
days to catch up with Earth and align with
it and the sun in a new moon phase.
What we observe from earth
How much of the
moon we see
depends on where
the moon is in its
orbit:
Appearance:
Appearance:
Appearance:
Lunar Eclipse
Lunar Eclipses
Solar Eclipse
Solar Eclipses
Tides
Are caused by the Moon
and Sun’s gravitational
pull on the water of the
Earth.
When the sun & moon form a right angle (90) with the
Earth water is pulled in all directions. This causes a
Neap tide. Water level is very constant.
The sun, moon, & Earth are in a straight line this is a Spring Tide.
There will be a very high High Tide and a very low Low Tide.