The Solar System
Nebula Theory
(our solar system)
• The solar system started from the
spinning and condensing of a cloud of
dust and gas. The greatest matter
formed the sun with the remaining
becoming the planets.
Inner Planets
• Terrestrial planets
– Mercury
– Venus
– Earth
– Mars
• Formed as small rocky material nearest to the
protostar(our sun) cooled.
Jovian (outer planets)
• Jupiter
• Saturn
• Uranus
• Neptune
Planets orbit in ellipses
Perihelion- when the
planet is closest to the
sun
Aphelion- when the
planets are farthest
away
Sun
http://astro.unl.edu/classaction/animatio
ns/sunsolarenergy/fusion01.html
•Core –nuclear fusion
occurs
– In nuclear fusion, the
nuclei of atoms are
physically joined together
to form greater mass
atoms. This process of
creating new elements is
called nucleosynthesis.
Most common is hydrogen to
helium
– Must occur at temperature
greater than 10 million
degrees C
Core
• In the core, mass is converted to energy by the
process of nuclear fusion.
• Einstein’s energy-mass equivalence equation explains
this:
• E = mc2
• In extreme conditions such as in the cores of stars,
matter is converted to energy.
• The energy in the core of the Sun is in the form of
gamma ray photons. As they move outward from the
core, they are absorbed and re-emitted many times,
and in the process, lose transfer some of their
energy.
Sun
•Radiative zone- energy moves
outward in waves
•Photons try to move outward from
the core where they are produced,
but the density is so great that
they are reabsorbed and remitted
many times. Each time they are
freed, it is in a random direction.
This process, called the random
walk, causes the solar photons to
be trapped inside this zone of the
Sun for anywhere between 100
000 to 1 million years.
•Convection zonewarmed gases rise and
cool gases sink
Convective Zone
At the bottom of the convective zone the temperature is
about 2,000,000° C. This is "cool" enough for heavier ions
(such as C,N,O, and Fe) to hold onto some of their
electrons. This makes it harder for photons to get through,
trapping pockets of heat that causes the fluid to "boil" or
convect.
This convection transports heat rapidly to the surface. The
fluid expands and cools as it rises. At the photosphere, the
temperature has dropped to 6000° C and the density is
only 1/10,000th the density of Earth’s atmosphere. The
tops of the convective bubbles are visible at the surface as
granules.
Photosphere
The photosphere is the visible surface of the Sun. It is the zone where
light breaks free and begins its journey through space.
Features of the Photosphere
Granules are the tops of
convection cells. They are
in constant motion, like a
pot of boiling oatmeal.
The white areas are rising,
while the dark areas are
falling.
Features of the Photosphere
Sunspots are dark areas that
mark places where magnetic
fields are breaking through the
photosphere. They usually occur
in groups or pairs.
The dark, inner area of the
sunspot is the umbra. It is about
1500°C cooler than the
surrounding photosphere.
The outer transition area around
the sunspot is the penumbra. It
has a temperature in between
the umbra and the photosphere.
Sunspot Cycle
Every 11 years, the
number of sunspots
builds from a
minimum to a large
number of sunspots.
This corresponds to a
direct increase in
solar activity. We are
now at the peak of
the sunspot cycle, a
time known as Solar
Max.
Sunspots and magnetic fields
Every 11 years, at the time of Solar Max, the
magnetic poles of the Sun reverse polarities.
Since each pole maintains a polarity for 11 years,
the full magnetic cycle of the Sun is 22 years.
CHROMOSPHERE
• Above the photosphere
• Reddish in color
• The Chromosphere is the
“lower atmosphere” of the Sun.
It glows red due to the
emission of red light from
hydrogen. This wavelength of
red light is known as
“Hydrogen-alpha” radiation.
• Sunspots: are temporary
phenomena on the photosphere
of the Sun that appear visibly as
dark spots compared to
surrounding regions.
– They are caused by intense
magnetic activity, which inhibits
convection
CORONA
• Outermost atmosphere of the sun
• Seen only during a total solar eclipse
• Very hot but thin
Solar Winds
• Corona prevents
most particles from
exiting the sun.
However, some
Ions/ particles
escape as Solar
Winds.
• Causes Auroras
(northern lights).
SOLAR FLARES- Large
Eruptions of Gas
Increases Auroras
Prominences: large, bright,
gaseous feature extending
outward from the Sun's
surface, often in a loop shape.
A coronal mass ejection
(CME): is a massive burst of
solar wind and magnetic fields
rising above the solar corona
or being released into space.
* Can only see corona
during an eclipse
SOLAR FLARES
CORONA
SUN SPOTS
PROMINENCE
SPICULES
CONVECTION ZONE
CHROMOSPHERE
PHOTOSPHERE
RADIATIVE ZONE
CORE
• An aurora is a
natural light
display in the sky
– Auroras are
caused by
charged particles,
mainly electrons
and protons
Increased solar flares activity
can interrupt communication
systems on earth