Transcript THE SUN - Halton District School Board

THE STAR OF OUR SOLAR SYSTEM
Solar radiation travels from the sun to the earth at the speed of light.
The speed of light is 300 000 km/s.
The sun’s energy does not travel to the earth instantaneously.
It takes about 8 minutes for solar radiation to reach the earth’s surface after leaving the sun.
http://www.youtube.com/watch?v=Gm
WNs4QrshY
http://www.youtube.com/watch?v=Gm
WNs4QrshY
SUN FACTS
The sun is the only star in our solar system.
• It is 1,000,000 times larger than the earth.
• The sun accounts for 99% of the mass of our
solar system and the planets make up the
other 1% of the mass.
• The planets are tiny specks of matter,
orbiting the Sun due to it’s gravity.
SUN FACTS CONTINUED
• The sun is a big ball of hot gas that
rotates once on its axis every 35 days.
• It is made of 75% hydrogen and 25% helium
gas.
• The pressure and temperature of the core
is so high that thermonuclear reactions take
place.
• These reactions produce a large amount of
energy.
WHERE IT ALL HAPPENS - THE CORE
• Hottest part of the sun (15,000,000oC).
• Region where the sun’s energy is first made
in a process called nuclear fusion.
• What is nuclear fusion?
• It is the process of merging the nucleus
of two smaller atoms to create one
larger one.
Nuclear Fusion
e-
1 p++
01npoo
0n
ee--
2 p+
2 no
e-
In the core, the sun’s large gravitation force compresses hydrogen atoms together and fuses their nuclei
creating helium atoms.
Each second the Sun converts about 600,000,000 tons of hydrogen nuclei into helium nuclei.
The fusion reaction creates an explosion in the core that causes massive amounts of energy to travel from
the interior outwards.
explosion due to nuclear fusion
force of gravity
The collapse of the Sun from its
own gravity is balanced by the
nuclear explosions at its core.
An enormous amount of heat and light moves through several layers or zones toward the outer
atmosphere of the sun.
The ratio of hydrogen to helium is changing as nuclear reactions continue to take place.
The Sun formed 4.5 billion years ago, and will run out of fuel (hydrogen) in about 5 billion years.
When this happens, the Sun will explode into a planetary nebula, a giant shell of gas that will
destroy the planets in the Solar System (including Earth).
How do we know what elements (e.g.hydrogen and helium) are
present in the sun and other stars?
One of the most useful devices that astronomers use to look at light given off by the sun
and other stars is a called a spectroscope.
 A spectroscope is a device that splits light into a pattern of colours so that we can see
them as separate lines of colours.
Works similar to a prism.
Each element that is heated or energized produces its own unique line pattern of colours that
can be seen when you look through a spectroscope.