The Sun

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The Sun
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FORMATION OF THE SOLAR SYSTEM
Solar Nebula Theory
- states that stars and planets form together
from contacting, spinning disks of gas and
dust.
Nebula
- a cloud of gas and dust
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How did our solar system form?

• a supernova (big explosion where the entire outer
  
• part of a star is blown off) sends waves in
  space
• that triggered a nebula to start spinning

b) as the nebula spins, it begins to collapse as
gravity pulls the gas and dust together
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c) the cloud spins faster and flattens the dust
and gas into a disc
d) the gas and dust collect in the centre
forming a hot condensed lump of matter
(protostar) which eventually becomes a star
e) small amounts of matter in the disc collect
and form bigger, rocky lumps called
planetismals.
f) those planetismals that survive collisions
turn into planets
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OUR STAR THE SUN

• as the nebula contracts, the gases that collect
  in the centre
• compress increasing the temperature of the
  protostar

• when temperatures reach 10 000 000oC we get

NUCLEAR FUSION!
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Nuclear Fusion

• the process that produces energy in the Sun.
• Hydrogen nuclei combine to form helium nuclei.
• Takes a lot of pressure and temperature
• Nuclear reaction

http//www.youtube.com/watch?vfSr3V498A3Ifeature
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PARTS OF THE SUN
CORE
- gravity pulls all the mass inwards creating
intense pressure forcing hydrogen atoms to
come together (nuclear fusion) to make
helium atoms
- Energy is transferred from core to outer parts
by RADIATION.
- The outer layers transfer energy by CONVECTION
CURRENTS.
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Structure of the Sun
PHOTOSPHERE
- called the surface of the Sun (not really a
surface since the Sun is made up of gases)
- 5500oC thousands of km deep
CHROMOSPHERE
- the inner atmosphere
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Structure of the Sun
CORONA
- the hot outer part of the Sun (1 000 000 oC)
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A GROWING SUN
- Helium is denser than hydrogen and settles in
the Suns core
- Helium core grows larger as well as the fusion
area around it
- Sun is getting larger 30 larger than when it
was born 5 billion years ago

• Sun has enough hydrogen fuel (for fusion) for 10
  billion years
• Our Sun has 5 billion more years left

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SUNSPOTS AND SOLAR FLARES
- Sun spots are areas of strong magnetic fields
(dark spots we see on the Sun 4500oC)

• start off small, then get larger, form clusters
  and eventually
• fade and disappear.
• They occur in 22-year cycles and seem to move on
  the Suns surface, which we believe is actually
  the Sun rotating.
• - When a magnetic field is so intense that the
  solar flare can eject intense streams of charged
  particles into space called
• solar wind.

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SOLAR WIND How does it affect Earth?

• Disrupt telecommunications
• and damage equipment
• aboard spacecrafts

• Harmful to astronauts
• (like x-rays on humans)

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3) Aurora Borealis (Northern Lights)
- The Aurora Borealis are caused by the solar
wind interacting with Earths magnetic field
- the gases in Earths upper atmosphere become
charged and produce light (strongest are the
Earths poles)
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http//www.youtube.com/watch?vxUYibQFIIVkfeature
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IMPORTANCE OF THE SUN

• Provides radiant energy for all life on
• Earth

• Keeps Earth in a steady
• orbit because of its
• gravitational pull.

3. Creates winds and ocean currents 4.
Microwaves, radio waves, X-rays, gamma rays
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