Download Stars and Constellations Power Point

Stars, Galaxies,
and Constellations
Stars
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Stars are born when
there is a large
amount of gas and
dust in a small area
that becomes so hot
that nuclear fusion
starts.
The gas continues to
burn until it runs out.
More burning gas = a
bigger and brighter
star!
Our Sun is a star and is the largest
object in our solar system. It is the
only star in our solar system
Our Sun
Billions of years ago, things may have been different
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The Sun was cooler (by up to 30%!)
Earth’s atmosphere was different (thicker, carbon dioxide)
Conditions will be different in the future
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By many accounts, increases in the Sun’s temperature will make Earth
uninhabitable in 1 billion years or less
Our Sun
The Sun will spend most of its life in the
main sequence.
 It will expand into a red giant
 In about 5 billion years, it will turn into a
white dwarf.
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The Sun compared to other stars in
our galaxy…
And yet larger stars…
Temperature of a Star
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3,000° – 6,000° Fahrenheit (1,649° – 3,316° Celsius): Red
6,000° – 8,500° F (3,316° – 4,704° Celsius): Orange
8,500° - 10,500° F (4,704° – 5,816° Celsius): Yellow/ White
10,500° – 13,000° F(5,816° – 7,204° Celsius): Type F -White
13,000° - 17,500° F(7,204° – 9,704° Celsius): Type A -White
17,500° – 50,000° F (9,704° – 27,760° Celsius): Blue -White
50,000° - 100,000° F (27,760° – 55,538° Celsius): Blue
What is a Galaxy?
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A large group of stars outside of our own Milky
Way
Made of billions to trillions of stars
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Also may have gas and dust
Spiral, or elliptical, or irregular shaped
Types of Galaxies
Spiral Galaxies
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Have arms of stars, gas
and dust that curve away
from the center of the
galaxy in a spiral form.
There is a central disk of
older stars at the center.
The youngest stars are
on the outer arms
There is a lot of dust and
gas
The Milky Way Galaxy
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We live in the Milky Way galaxy.
The Milky Way is a spiral galaxy.
It has about 200 billion stars, and
lots of gas and dust.
All the stars in the
Milky Way have their
own motion, some are
moving towards the
sun while others are
moving away from
our sun.
Our Sun is halfway to the edge
of an arm, revolving at half a
million miles per hour around the
center of the galaxy
The Milky Way Galaxy
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The Milky Way has
a diameter of
about 100,000 light
years.
The nucleus is 2000
light years thick.
Our sun is located
30,000 light years
from the nucleus.
It takes the sun 200
million years to
make one
Revolution
around the center.
The Milky Way Galaxy
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You can look
outside on a clear
dark night and see
the Milky Way!!!
In the night sky it
will appear as a
band of stars that
stretches across
the sky.
It will appear
“milky” in the sky.
You are actually
looking at one of
the arms of the
galaxy!
Types of Galaxies
Elliptical Galaxies
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Elliptical galaxies contain
many older stars, up to
one trillion, but little dust
and gas.
They are typically larger
galaxies.
There are no young
stars.
Types of Galaxies
Irregular Galaxies
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They lack shape
They are the smallest
galaxies with the fewest
stars.
Could be formed
from the collision
of two different
galaxies.
Stars are of low
mass and cannot
organize into a
pattern
The next closest galaxy to us is
Andromeda, which is also a spiral
galaxy. Andromeda is about 2.5
million light years away.
There are an estimated
50 billion to 1 trillion
galaxies in the known
universe!
What is a Nebula?
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A cloud in space
Made of gas and dust
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Can have stars inside
Most of the ones we see are inside our Milky
Way Galaxy
 Young stars form
in nebulae
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WHAT ELSE IS IN A GALAXY?
the nebula’s cometh
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Galaxies also
contain gases and
dust.
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There are two
bright nebulas.
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One glows bright
from the hot gases
within.
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The other shines by
reflecting light
from nearby stars.
THE DARK SIDE OF THE NEBULA.
The dark nebula.
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other nebula’s are
dark in nature.
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Dark nebulas are
visible as dark areas
among the stars.
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Dark nebulas absorb
light of more distant
stars behind them.
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The Horsehead Nebula
is an example of a
dark nebula.
Leftovers from an Explosion
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Supernova- A Massive Star Explodes
Neutron Star or Pulsar
A neutron star is a type of stellar remnant that can
result from the gravitational collapse of a massive
star
Black Holes
•A black hole is a region of spacetime from which nothing,
not even light, can escape.
•Black holes of stellar mass are expected to form when very
massive stars collapse at the end of their life cycle.
•After a black hole has formed it can continue to grow by
absorbing mass from its surroundings.
•There is general consensus that supermassive black holes
exist in the centers of most galaxies
Light Years
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What is a Light Year?
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A light year is the distance light travels in a year. Light moves at
a velocity of about 300,000 kilometers (km) each second; how
far would it move in a year?
About 10 trillion km (or about 6 trillion miles).
Parallax
Parallax is a difference in the apparent
position of an object viewed along two
different lines of sight.[
 Astronomers use the principle of parallax
to measure distances to celestial objects
including to the Moon, the Sun, and to
stars beyond the Solar System.
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Binary Star Systems
A pair of stars that revolve
around each other.
 Multiple star systems- have
more than two stars. Two
will orbit rapidly around
one another while a third
will move slowly at a
greater distance away.
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Constellations
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All the stars that we
can see from Earth
are in our galaxy.
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Constellations are
patterns of stars in
the sky.
Ancient Greeks and Romans saw pictures
in the stars of the night sky.
 These pictures were later associated with
myths.
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Astronomers recognize 88
constellations including…
14 men and women
 9 birds
 2 insects
 19 land animals
 10 water creatures
 2 centaurs
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A serpent
 A dragon
 A flying horse
 A river
 1 head of hair
 29 inanimate
objects
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Example: Scorpius
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The scorpion is believed
to be responsible for the
death of the great hunter,
Orion.
Orion was stung and
killed after he was
boasting that he could
defeat any beast.
Scorpius was placed in
the sky opposite from
Orion to avoid any further
contact.
Stars as Tools for Navigation
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Earth rotates on its
axis, this makes
most constellations
appear to rise in
the east and set in
the west during the
night.
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There is a group of
stars that appear in
the sky all night long
and all year long. It
seems that these
stars do not rise and
set, but circle the
Earth’s north pole
each night. These
stars are called
circumpolar.
Stars as Tools for Navigation
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The North Star is called
Polaris and located
directly above the North
Pole. This star appears
in the same place every
night all year long.
In the Northern
Hemisphere, if you find
Polaris you will be able to
tell which direction is
north.
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The Southern
Hemisphere does not
have a star to help you
find its pole. In stead it
has what is known as the
Southern Cross.
The Southern Cross
consists of 4 bright stars
and some dimmer ones.
All of these together point
to the south pole.
Extra Info.
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The brightest constellation is Crux (the
Southern Cross). The constellation with
the greatest number of visible stars in it
is Centaurus (the Centaur - with 101
stars). The largest constellation is Hydra
(The Water Snake) which extends over
3.158% of the sky.