Transcript SNC 1D The Sun

The Sun
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
How did our solar system form?
a) 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
http://www.youtube.com/watch?v=tFLOsRSuW0E&feature=related
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
OUR STAR – THE SUN
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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!
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?v=fSr3V498A3I&feature=related
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.
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
Structure of the Sun
CORONA - the hot outer part of the Sun (1 000 000 oC)
A GROWING SUN
- Helium is denser than hydrogen and settles in the Sun’s 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
SUNSPOTS AND SOLAR FLARES
- Sun spots are areas of strong magnetic fields (dark spots we
see on the Sun; 4500oC)
-
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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 Sun’s
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.
SOLAR WIND – How does it affect Earth?
1) Disrupt telecommunications
and damage equipment
aboard spacecrafts
2) Harmful to astronauts
(like x-rays on humans)
3) Aurora Borealis (Northern Lights)
- The Aurora Borealis are caused by the solar wind interacting
with Earth’s magnetic field
- the gases in Earth’s upper atmosphere become charged
and produce light (strongest are the Earth’s poles)
http://www.youtube.com/watch?v=xUYibQFIIVk&feature=PlayList&p=60FA28
55CF33865F&index=45
IMPORTANCE OF THE SUN
1. Provides radiant energy for all life on
Earth
2. 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
http://www.youtube.com/watch?v=gdLaPhNBOcU&feature=related