Download Weathering, Erosion and Mass Movement

Be humble, for you
are made of dung.
Be noble, for you
are made of stars.
SERBIAN
PROVERB
OBJECTIVES
Explore the structure of the Sun.
Describe the solar activity cycle and
how the Sun affects the Earth.
Compare the different types of spectra.
Sun
All stars, including
the Sun, have the
following identical
composition:
 25 percent helium
 73 percent hydrogen
 and 2 percent other
The Sun contains 99
percent of the mass
in the solar system,
it controls the
motion of the
planets.
- The scale
Just how
big ?
The solar interior is not solid, but
gaseous, because of its high
temperature.
Other than the use of special
instruments, the chromosphere is
only visible during a solar eclipse
when the photosphere is blocked.
In the convective zone of the solar interior, volumes of
gas carry energy to the Sun’s surface.
The outermost layer
of the Sun’s
surface from which
most of the light
emitted by the Sun
comes is the
photosphere.
The photosphere
is the Sun's
visible surface,
due to its high
temperature, it
glows yellow.
The top layer
of the Sun’s
atmosphere is
the low-density
corona.
The solar wind flows outward from the
corona to the entire solar system.
Solar activity cycle is
minimum to maximum
sunspots over a period
of 22.4 years.
Due to a reversal of
polarity.
Sun spots are caused by
magnetic fields
In the 1600s, the solar activity cycle stopped, and
there were no sunspots for nearly 50 years.
No sun spots equaled mini ice-age!
A prominence is an
eruption of hot gas
that can extend
thousands of Km into
space from the surface
of the Sun before
cooling and condensing
and then rains back to
the surface.
Earth is
bombarded with
particles and
radiation after
violent eruptions
from the Sun’s
surface called
solar flares.
The energy that reaches our planet
from the sun is 1354 J/m2/sec
That’s enough to operate ~10 - 100
Watt bulbs within each 1-m2 area.
The Spectrum is visible light
arranged according to wavelengths.
A non-compressed
gas produces a
spectrum in which you
see bright lines at
certain wavelengths,
this is called an
emission spectrum.
The dark bands
observed in a
solar spectrum
are caused by
different
chemical
elements which
absorb light at
specific
wavelengths.
OBJECTIVES
Describe star
distribution
and distance.
Classify the types
of stars.
Summarize the
interrelated
properties of
stars.
A group of bright stars named for
Ursa Major “Big
an animal, a mythological
Dipper”
character, or an everyday object
is called a constellation.
Cassiopeia
Polaris
“North Star”
BELCHERTOWN, MASSACHUSETTS
W072, N42
http://www.neave.com/planetarium/
A star that is gravitationally bound to another
star can either be part of a star cluster or a
binary star.
Astronomers can sometimes identify binary stars
even if only one star is visible.
The speed of light is:
299,792.458 km/s
The Speed of Light:
It’s Not Just A Good Idea
It’s the Law.
(670,616,629 mph)
Light-year (ly)  Distance traveled by light
in one year
9.461 X
12
10
Km
Parsec (pc)  3.26 ly, or . . .
3.086 X
13
10
Km
The apparent shift in a star’s position caused by the
motion of the observer is called parallax.
Using the parallax
technique, astronomers
can accurately measure
the distance of stars up
to 500 pc away.
One of the most basic observable
properties of a star is brightness, the
classification was established by the
ancient Greeks.
In the modern classification
of apparent magnitude, a
difference of 5 magnitudes
corresponds to a factor of
100 in brightness.
Absolute magnitude takes distance into account when
indicating the brightness of a star.
Apparent & Absolute Magnitude
Both classify the brightness of stars.
Apparent
Absolute
• how bright a star appears • takes into account
to be.
differing distances and
measures brightness at a
distance of 10 parsecs.
The HertzsprungRussell diagram
(H-R) diagram,
first plotted in
the twentieth
century,
demonstrates the
relationship of
luminosity and
temperature.
O – B – A – F – G – K – M
Spectral Sequence
Stars are assigned a
spectral type, with M
being the coolest
stars.
The section of the H-R diagram into which about 90 percent of
stars fall is called the main sequence.
30.2 Measuring the stars Quiz (10 pts)
QUIZ HERE
OBJECTIVES
Explain how astronomers learn about the
internal structures of stars.
Describe how the Sun will change during its
lifetime and how it will end up.
Compare the evolutions of stars with
different masses.
Nebula is a
cloud of
interstellar
gas and dust
that collapses
on itself to
form a new
star.
One principle used
by astronomers to
understand the
basic structure of
stars is
hydrostatic
equilibrium .
Fusion is combining of lightweight nuclei into
heavier nuclei, such as four hydrogen nuclei
combining to form a helium nucleus.
Stars on Main
Sequence all
produce energy
by fusing
As a star ages, its internal composition changes
as nuclear reactions in the star’s core convert
one element into another.
May Fuse
Helium  Carbon
Carbon  Oxygen
Only 10% of a
star's mass
undergoes fusion
because
temperatures
outside of the
core never get
hot enough for
reactions to
occur.
What happens next ? depends on the...
The main sequence lifetime of a low-mass
star is much longer than the lifetime of the
Sun.
The helium-reaction phase for a star the size
of the Sun lasts only one-tenth as long as the
hydrogen-burning phase. The result is a core
made of carbon and it is a white dwarf.
Following the end of each reaction stage,
a massive star becomes a red giant
several times.
When the core of a
star collapses
forever, the
extremely dense
object that remains
is called a black
hole.
is a small, massive, dense object that has a gravity so
immense that nothing—not even light—can escape it.
FUSION
FISSION

is the process of
splitting heavy atomic
nuclei into smaller,
lighter atomic nuclei


is the combining of
lightweight nuclei into
heavier nuclei
much more energy
being released
30.3 Stellar Evolution Quiz (10 pts)
QUIZ HERE