Transcript Characteristics of Stars PLATO

Stars
Our sun is a
star!
Solar
Prominence
Solar Flare
Total Eclipse
Partial Eclipse
Solar Eclipse:
Moon blocking the sun
We are going to
go BIG:
Universe
• All of Space and everything
in it
•Includes
billions of
galaxies!
Galaxy
• A cluster of
millions or
billions of stars
What Galaxy do we live in???
• The Milky Way!!!
• There are billions of other
galaxies in the universe.
• There is a lot of empty space
between galaxies
There are billions of
Galaxies in the Universe.
Some are very small with
only a few million stars.
While others could have as
many as 400 billion stars, or
even more.
One of the deepest images of
the sky taken to date with
NASA's Hubble Space
Telescope reveals a population
of faint blue galaxies.
This cluster of galaxies can
be found in the constellation
Draco, some 2 billion lightyears from Earth.
This is a galaxy.
This is a galaxy.
This is a galaxy.
Vocabulary
GALAXY - a huge group of stars,
dust, gas, and other celestial
bodies bound together by
gravitational forces.
Kinds of Galaxies
There are three kinds of Galaxies,
Spiral, Elliptical, and Irregular. The
only difference between the three is
what shape they are.
Elliptical
Spiral
Irregular
Draw and label
the three
different types of
galaxies.
Spiral galaxies are
galaxies whose main
component is a flat
disk with a central
bulge from which
several arms wind
their way around the
center toward the rim.
Spiral Galaxy #M109
Spiral Galaxies
are like a plate,
so they look flat
from the side,.
The Andromeda Galaxy is the closest
major galaxy to the Milky Way, and the
farthest object that can be seen with the
naked eye. It is about 2,400,000 light-years
from Earth, so it takes 2.4 million years for
the light from there to reach us!
An irregular galaxy is
a galaxy with no
symmetry. Irregular
galaxies get their odd
shapes in many ways.
One way irregular
galaxies are formed is
when galaxies collide
or come close to one
another, and their
gravitational forces
interact.
Can you name each galaxy?
SPIRAL
1. __________
ELLIPTICAL
IRREGULAR
3. __________
2. __________
Vocabulary
SPIRAL GALAXY - flat disk with a
central bulge from which several arms
radiate.
ELLIPTICAL GALAXY – smooth,
elliptical/round shape.
IRREGULAR GALAXY – no
symmetry, no patterns.
Galaxies often crash into one another. Even
our own galaxy has had others pass right
through it. Don't worry though, galaxies can
pass through each other quite safely. Stars
are so far apart that the chances of two
colliding is very unlikely.
THE
MILKY
WAY
GALAXY
The Milky Way as seen from Earth
Milky Way Galaxy
Our Solar System is located
in the far reaches of a spiral
galaxy that we call the Milky
Way Galaxy. Almost all of the
stars that we see in the night
sky are also members of the
Milky Way Galaxy. The Milky
Way Galaxy contains
roughly 200 billion stars,
one of which is our Sun.
What type of galaxy
is the Milky Way?
Irregular
Spiral
Elliptical
The correct answer is…
Spiral
What is a Solar System?
• One star and everything that
orbits the star.
• Our solar system has the sun, 8
planets (Mercury, Venus, Earth,
Mars, Jupiter, Saturn, Neptune),
Pluto and possibly other dwarf
planets, and asteroids.
Our solar system:
8 Planets and the Sun
Light-Year
• The distance light travels in
one year
• Unit of Distance
Fun Fact:
• It takes a little over 8 minutes for light
from out sun to reach Earth.
• The light you see in the sky left the
sun 8 minutes before you looked!
• Light from other stars will take many
years (Even Millions of years!) to
reach us, so when you look at stars
you are really looking into the past!
Parallax
• Apparent Change in
position of an object when
you look at it from different
places.
Click for parallax animation…
• http://instruct1.cit.cornell.edu/courses/astr
o101/java/parallax/parallax.html
• The more a star moves, the closer it is to
Earth!
How Stars are Classified
• Size
• Temperature
• Brightness
A Star’s Brightness is
Determined in 2 Ways:
• Apparent Magnitude
• Absolute Magnitude
Apparent Magnitude
• A star’s
brightness as
seen from Earth.
• Stars that are
closer to Earth
look brighter.
Absolute Magnitude
• The brightness a star would
have if it were a standard
distance from Earth.
Hertzsprung-Russell
Diagram
• H-R Diagram
• A graph comparing the
brightness and temperature
of stars.
Brightness
Temperature in Kelvins
H-R Diagram:
• When you graph Temperature
(Star Color) and Brightness of
many stars, you get patterns.
• Astronomers have studied the
patterns on the graph and have
learned many things about stars.
A Star is Born!
• Stars are formed in nebulas.
• A nebula is a huge cloud of
dust and gas somewhere in
space.
Lagoon Nebula
Orion Nebula
Eagle Nebula
Inside the Nebula…
• Gravity pulls some of the
gas and dust together
into a clump.
• As the clump gets
bigger, it starts getting
hot.
Inside the Nebula…
• After many millions of years the
clump is big enough and hot
enough for nuclear fusion.
• Nuclear fusion: When atoms are
so hot and moving so fast they
melt together and release energy.
• You can see some of the energy
as light and feel heat!
Nuclear Fusion:
• Most stars are made of
hydrogen atoms.
• When 2 hydrogen atoms fuse
together they make a new
atom of helium.
A star is born…
• When a star first gives off energy
it is called a protostar.
• As it fuses atoms together it is a
main sequence star.
–90% of the stars you see in the sky
are main sequence stars.
• As the star runs out of fuel, it will
grow larger and cooler and
become a Red Giant. (Cool, dim)
–Huge stars with lots of fuel can
become a Supergiant
– It is like taking the wood from a burning
campfire and spreading it out across the
beach. It gets cooler and dim, but takes
up more space.
A Star Dies…
• Red giants made from small and
medium stars will slowly lose their
outer layer of gas.
• The fuel that is left will be in a hot
core that will shine as a white
dwarf. (Small, hot star)
A Star Dies…
• Red giants made from large stars
may explode into a supernova.
– Some of the star pieces may form a
new nebula, which starts the cycle over
again.
A Star Dies…
• Most stars that go supernova will
leave behind a neutron star,
which is only about 20 km across
but very dense.
• Neutron stars give off radio
waves!
• A few huge stars will become a
black hole:
–The matter left from the explosion
gets packed really tightly, so it is
very dense.
–This very dense matter has so
much gravity not even light can
escape.
–It is about 30km across, but 5 times
more mass than the sun.
How long do stars shine?
• It depends on the mass of the star:
–Bigger stars have more mass and burn
fuel faster. (Like big trucks)
–Smaller stars use less fuel (Like cars)
So:
The bigger the star, the sooner it runs
out of fuel and dies!
How do scientists know this???
• Astronomers have looked at many
different stars, some very old and some
very young.
• They make graphs to compare the stars
color, size, and what kind of atoms they
are made of. (Like the H-R diagram)
• They use this data to make conclusions.
The sun is our star…
• The sun is a medium-mass star,
so it will NOT go supernova.
• Medium-mass stars live for about
10 billion years.
• Our sun is about 4.6 billion years
old right now, so it is ½ way
through its life.
Origin of the Universe:
• Scientists believe the universe we
see today began with a giant
explosion called the big bang.
• Astronomers estimate the
universe is 10-15 billion years old.
Why do they think this???
• All the galaxies and stars we see
are moving away from us at top
speed, just like pieces of
something that exploded.
–There is more data, such as
background radiation and other
calculations that fit this theory.
Big Bang
How did our Solar System get here?
• The big bang left dust and gas in
nebulas.
• The gravity between the dust
made it spin around and come
together into clumps.
• A very large clump in the center
became the sun.
How did our Solar System get here?
• Smaller clumps of matter spinning
around the sun became planets.
• The 4 inner planets lost most of
their gas because they were too
hot. (Mercury, Venus, Earth, Mars)
• The 4 outer planets became gas
giants. (Pluto, Saturn, Uranus, Neptune)
Our solar system:
8 Planets and the Sun