Download STARS

STARS
DISTANCES IN THE
SOLAR SYSTEM
• Our Sun is the closest star to us.
• Distances in the solar system are so
big that we use a large unit of
measurement.
• A LIGHT YEAR is the distance light
travels in one year.
WHAT IS A LIGHT YEAR?
Consider the following:
– Light travels 300 000 km every second.
– There are 31 536 000 seconds in a year
Distance = speed x time
– Therefore, if we multiply the numbers
together, we get 10 trillion km,
or 10 000 000 000 000 km!
LIGHT YEARS, CONT’D
• The closest star to us,
Alpha Centauri A , is
4.3 light years away.
• This is equivalent to
43 000 000 000 000
km away from us!
WHAT IS A STAR?
STAR: A collection of matter that
emits huge amounts of energy.
STARS are classified based on four
characteristics:
1.Colour
2.Temperature
3.Size
4.Brightness
COLOUR & TEMPERATURE
COLOUR
Temperature Range (C)
Blue (ex. Zeta Orionis)
25 000 – 50 000
Bluish-White (ex. Rigel)
11 000 – 25 000
White (ex. Sirius)
7500 – 11 000
Yellowish-white (ex.
6000 – 7500
Polaris)
Yellow (ex. Sun)
5000 – 6000
Orange (ex. Arcturus)
3500 – 5000
Red (ex. Betelgeuse)
2000 - 3500
• Stars glow because
they are very hot.
SIZE OF STARS
GIANTS AND DWARFS
• When a star begins to reach “old age” the
pressure inside runs out as all the hydrogen
runs out.
• As the star gets older, it swells in size.
• Our Sun will become a Red Giant as it runs
out of fuel.
• When it “dies” it will become a white dwarf.
• Our Sun is bigger than 95% of the stars in
the Universe.
• The Size Of Our World
OTHER ASTRONOMICAL
STUFF…
SUPERNOVA
• An enormous explosion when a large star
dies.
• When all the hydrogen is used up the core
collapses
• The absence of pressure causes a neutron
star or a black hole.
• The explosion can be bright enough to see
during the day!
OTHER ASTRONOMICAL
STUFF…
NEUTRON STAR
• These stars are
ten times bigger
than our Sun.
• It become a dense
core of neutrons.
• A PULSAR is a type
of neutron star.
OTHER ASTRONOMICAL
STUFF…
BLACK HOLE
• These are stars thirty times bigger
than our Sun.
• Small, very dense object with an
extremely strong gravitational pull.
• Nothing can escape from it; not even
light.
OUR SUN
• The Sun’s energy comes from
NUCLEAR FUSION, a reaction that
takes place under high temperature
and pressure.
• Nuclear Fusion
OUR SUN
The Sun has multiple layers:
• Core: Nuclear fusion takes place
here, and temperatures can reach
15 million °C.
• Photosphere: The surface of the Sun,
made up of moving gases; average
temperature of 5500 °C. Sunspots
occur here.
OUR SUN
• Chromosphere: the inner
atmosphere of the Sun
• Corona: The hot outer layer of
the Sun; temperatures reach 1
million °C.
OUR SUN
Other features of the Sun:
• Solar Prominence: an explosion of
glowing gases from the chromosphere
that can last for weeks and reach
40,000 km high.
• Solar Flare: Like a solar prominence,
but the gases travel into the corona,
and last only a few minutes.
GALAXIES & STAR
CLUSTERS
• Galaxy: a collection of gas, dust, and
hundreds of billions of stars.
• Our Sun is located in the lesspopulated spiral arm of the Milky Way.
GALAXIES & STAR
CLUSTERS
• There are approximately 400 billion
stars in our galaxy.
• The majority of the stars are located
in the central bulge.
Unusual Galaxies
• Quasars: Astronomical objects that
look like very faint stars, but emit
hundreds of times more energy than
entire galaxies.
• Scientists do not know the reason for
the intense light output.
STAR CLUSTERS
• Star Clusters: groups of stars that
are close together and travel as a
group (as few as 10 or as many as 1
million).
Ex. Pleiades