Download The Sun - Hicksville Public Schools

The Sun
The Sun
• Is by far the closest star to the
Earth
• Stars are luminous bodies
that create their own energy
through Nuclear Fusion
• The Sun is an average star
Nuclear Fusion
• Gravity causes clouds of dust and gases
in space to contract and heat until fusion
begins
• We use fission on earth (uranium and
plutonium) which does not produce as
much energy as fusion
• We only can use fusion for H-bombs
Sunspots
• The sun contains
sunspots which are
temporary storms on
the sun’s surface.
• They provide
evidence that the sun
rotates once every 27
days.
Before the invention of the
telescope, the Sun was thought to
be a perfect disk. However as
soon as telescopes became
available, astronomers turned
them to the Sun. They
discovered two things. Sunspots
and blindness. Not the great
scientist Galileo though, he was
far too clever and sensible. He
observed only at sunset and
sunrise and by projecting the
light onto a screen rather than
trying to look through the
telescope itself. He drew his
results very carefully. (1612)
Telescope Image of Sunspots taken from
Swedish Institute of Solar Sciences
Evolution of a Star
Life of a Star
• Stars like the sun spend most of their life on
the Main Sequence.
• When the Sun’s core is all fused to He, the sun
will expand and become a Red Giant.
• When the fuel is used up it will collapse into a
White Dwarf and then a Black Dwarf
• Stars more massive than the Sun will go
supernova.
Life Cycle of Stars
Stellar Evolution
A supernova is the final explosion
of a massive star, of more than
eight solar masses. It causes a
brief burst of radiation that may
outshine the entire galaxy, before
fading from view over several
weeks or months. During this
short interval, a supernova can
radiate as much energy as the
Sun would emit over 10 billion
years. The explosion expels much
or all of a star's material at high
velocity, driving a shock wave
into the surrounding interstellar
medium, where it sweeps up an
expanding shell of gas and dust
called a supernova remnant.
Cassiopea A
Tracking a Stellar Mass
H-R Diagram
Luminosity and Temperature of
Stars (ESRT)
Interactive HR
Diagram
Quesitons
Questions
1. In which group are the stars most
varied in both size and luminosity?
• Main Sequence
2. The sun is more luminous than any stars
in which group?
• Dwarf
3. State one way in which the Sun and
Polaris are similar and one way in which
they are different.
•Similar in temp. Different in luminosity
4. Why is Betelgeuse more luminous than
St. Barnard’s star?
•It is much larger/more massive