Transcript Our Universe

Our Universe:
Creation, Galaxies, Stars and Celestial
Objects
BIG BANG
THEORY
• universe began with one huge exploding atom that
relapsed all the energy and matter that exists today
• 13.8-15 Billion years ago
• Hydrogen and Helium, the make-up of stars, were
the first two elements formed in less than a
quarter of a second!
• explosion was so
enormous, that all
objects in the universe
are still moving
outward today from the
initial blast!
• radiation from this
explosion is also still
traveling across our
universe in the form of
microwaves (a specific
type of energy)
Big Bang Timeline
Evidence of Big Bang
• Background radiation is the
aftermath of gas, dust and
energy from the initial
explosion that is found in
every part of our universe.
• It proves that there
definitely was some
explosion beyond enormous,
billions of years ago!
RED SHIFT
• shift towards the red end of the spectrum of
colors given off by objects in space
• demonstrates that an object is moving away
from us and everything else
• is evidence of the “push” from the initial Big
Bang
• BLUE shift would demonstrate that an object
is moving TOWARDS us!
Absorption Lines from a supercluster of galaxies
Common Questions about BIG BANG
• Where is the center of the Universe?
– There no center of the universe because there is
no edge of the universe
– In a finite universe, space is curved so that if you
could travel billions of light years in a straight line
you would finish back where you started.
– It is also possible that our universe is infinite. In
both examples, groups of galaxies completely fill
the universe and are moving apart at all points
making the universe expand
Where did the Big Bang occur in
the Universe?
• Space and time were created in the Big Bang.
At the beginning of the universe, the space
was completely filled with matter.
• The matter was originally very hot and very
dense and then expanded and cooled to
eventually produce the stars and galaxies we
see in the universe today.
Is the Earth expanding with the
universe?
• The Earth is not expanding and neither is the
Milky Way galaxy.
• These objects formed under the influence of
gravity and stopped moving apart.
• Gravity also holds galaxies together into
groups and clusters. It is mainly the groups
and clusters of galaxies that are moving apart
in the universe.
What exists outside the universe?
• Space was created in the Big Bang. Our
universe has no edge or boundary - there is no
outside of our universe.
What existed before the Big Bang?
• Time was created in the Big Bang - we do not
know if it existed before the Big Bang.
• Some theories suggest that our universe is
part of an infinity of universes (called a
multiverse) which are being continuously
created. This is possible but very hard to
prove.
Future of the Universe
Open Universe
• theory states that everything in the
universe will continue to move
outward and away with continual
expansion infinitely
• Eventually, all stars would burn out
leaving our universe with empty
darkness.
Closed Universe
• This theory supports the idea that
eventually that outward expansion from
the initial Big Bang will wear.
• At this point, the force of gravity will
begin to pull everything back together
again.
• Then, another Big Bang will occur!
FLAT UNIVERSE
• A flat universe results if the
expansion slows to a halt in an
infinite amount of time but never
contracts.
• Expansion occurs so slow that it
appears to have stopped.
3 Types of Galaxies
Galaxy- a cluster of billions
and trillions of stars bound
together by gravity
Elliptical Galaxy
• round and
flattened
ovals
• (This is the
most
common type
of galaxy)
• Messier 32 (2.65
million light-years away in the
constellation Andromeda)
Irregular Galaxy
• smaller
galaxies
with no
distinct
shape
• Ex: Magellanic
Clouds (160,000 light
years away)
Spiral Galaxy
• Galaxies with
spiraling arms
that rotate
around a
central bulge of
massive
substance in
the center.
THE MILKY WAY
• spiral galaxy
• center is full
of extremely
massive, Red
Super-Giant
Stars
• center is over
28,000 light
years away
• 1 light year (which is measure of distance,
NOT time) is the distance light travels in a
year. Light travels at a speed of 9.5x1015
m/s!!!
• Which means it takes ________years for the
light of the stars in the center to travel
through space and be seen by our planet!!!
• The direction towards the center is toward
the constellation Sagittarius
• Our galaxy contains over 200 billion stars!
STATISTICS AND FACTS
• Sun orbital speed around the center is
220km/s, orbital period is 240 million years.
• The sun will complete 20 revolutions around
center in its lifetime.
• It is believed that there may be a massive
black hole at the center of our galaxy pulling
the massive supergiants in!!
• Most stars in MW are 207,000 AU (AU=
distance between sun and earth) apart, but in
the center they are only 1000Au apart
• AU = 149,597,871 km (92,955,807 miles)
Life Cycle of a Star
White dwarf will
eventually stop
nuclear fusion
and become a
black dwarf”Dead Star”
Medium
Star
Gravity condenses the
star to shrink
(Where protostars are
formed)
Giant Star
Nebula- the birth of a star
Orion Nebula
A Nebula is a cloud of cosmic
gas and dust where stars are
formed.
•gases of these nebulas are
mostly hydrogen and helium (the
two gases that make up all
stars!)
•Gravity begins to pull the gases
inward during the birth of a star.
•Then, with gravity, the density
of the gases increases which
causes the pressure and
temperature to increase, until
the star finally stabilizes.
Lagoon Nebula
Horsehead Nebula
• A star can exist anywhere from 1
Million to 30 Billion years!
(depending on size)
• Our Sun has around 5 Billion years
remaining. It is predicted to only
exist for 10 Billion total years.
YOUNG STARS
• Protostar:
• A baby star - formed in the nebulas after the gases have
condensed enough to begin nuclear fusion
• In Nuclear fusion, hydrogen atoms are converted into helium,
releasing the ENORMOUS amount of energy that causes stars
to become very hot!
• The amount of energy released per gram of mass is equal to
the amount of energy released by 22,000 tons of TNT. (The
nuclear explosion at Hiroshima only released an amount
equal to 13,000 tons of TNT)
Medium Stars
• Temperature= 6000°C
• Color = yellow/orange
• Example= Our Sun
(closest star is proxima
centauri)
• Size= over 90 million
miles in diameter!
(actually measured in
solar radii)
GIANT STARS
• Color= Red or
Blue
• Temperature=
4500°C
• Size= 10 x time
the size of the
Sun
RED SUPERGIANT STARS
• Color= Red
• Temperature= 3000°C
• Size= 1000 x the size of
the Sun!!
• As size increases, temp.
decreases because the heat of
nuclear fusion is spread out over
such an enormous volume!
SUPERNOVA (PLANETARY NEBULA)
• If a star is extremely massive, the
extreme density of the core
collapses under the gravity
causing a stellar explosion
known as a supernova.
• The catastrophic explosion
releases elements and cosmic
dust for millions of the years.
• These explosions are more
intense than 1 million nuclear
bombs!
Actual Supernova70 mill light years
away and occurred
millions of years ago!
Why are supernovae important to us?
• These explosions create the heavier
elements that are used and make up
humans!!!
• If a star has a lower mass, it will eventually
shrink to a planetary nebula.
• The planetary nebula then condenses to a
white dwarf and eventually a black dwarf.
BLACK DWARF or DEAD STARS
Both images are computer
animations. Black Dwarfs do not give
off any light to be seen.
• These are stars that have
burned out and nuclear
fusion is no longer
occurring, therefore these
stars are creating no
energy.
• Pressure causes these
stars to become
extremely dense, similar
to squeezing an aircraft
carrier into a glass jar!
WHITE DWARF STARS
• Color = White
• Temperature=
15,000°C
• Size= Average
around the
size of Texas
Neutron Star
Color: Blue
Temperature: 35,000°C
Size: A little larger than New York City
(5-10 Miles)
•is extremely dense and small.
•As the star decreases in size,
the pressure increases so
immensely that the temperature
increases dramatically.
•As temperature increases, so
does brightness.
•A Neutron Star is almost 1.5
million times brighter than our
Sun!
Color of Stars
• Stars are different
colors depending on
their distance, energy,
age and temperature
• Blue stars are the
HOTTEST
• Red stars are COOLER
than blue stars
Brightness
• The distance of a star affects its brightness
• APPARENT Magnitude is how bright a star
is depending on how far away it is from us
on Earth
• ABSOLUTE Magnitude is how bright a star
is, assuming that ALL stars are the SAME
distance away!
For Example:
• The sun’s absolute magnitude is
+ 5, in
comparison to other stars it’s not that
bright
• The sun’s apparent magnitude is
-26.8
because to us, the sun is close and very
bright
H-R Diagram
• Hertz sprung-Russell diagram
–Shows relationship between a star’s
surface temperature and it’s absolute
magnitude (actual brightness)
–Usually a star will follow a diagonal
line down the H-R diagram during it’s
life time, this is called the MAIN
SEQUENCE
BLACK HOLES
• a theoretical space where the gravitational
pull is so incredibly strong that no radiation,
including heat and light, can exist
• These black holes are a million to a billion
times more massive than our sun!
• Is there a black hole in the center of our Milky
Way- YES!
These are computer animationstrue black holes cannot be seen
because light cannot reflect off
them to create a shape.
• descriptions of black holes are based on equations in
the theory of general relativity developed by Albert
Einstein in 1916.
• The surface of a black hole is known as the event
horizon.
• This is not a normal surface that you could see or
touch. At the event horizon, the pull of gravity
becomes infinitely strong. Thus, an object can exist
there for only an instant as it plunges inward at the
speed of light.
GALACTIC BLACKHOLES
• weighing a few
billion times the
mass of the sun,
most galaxies have
a supermassive
blackhole in their
center.
• (ours is slightly
smaller than our
solar system!)
This is an actual black hole in the
center of our galaxy. The black
hole cannot be seen but we can
see its gravitational pull “eating”
everything around it
Variable Stars
•Variable Stars- stars
that pulsate in
brightness because of
the expansion and
contraction of their
outer layers, or the
blocking of their light
by another object.
•are brightest at their
largest diameter and
dimmest at their
smallest diameter.
Dark Matter and Dark Energy
• a “force” that is believed to
be like an anti-gravitational
force.
• 78% of universe is dark
matter
• Dark matter and dark energy
are still undefined today.
• We believe it consists of
subatomic particles, smaller
than protons and neutrons
• Scientists recognize the
effects of dark energy, but
they still do not know
exactly what it is.
ASTEROIDS
• large pieces of rocky debris, some larger than
our moon.
• Most are located in the asteroid belt between
Mars and Jupiter
• do not have a specific orbit, they cluster in the
belt and are continuously knocked out or
pulled in my Jupiter.
Images of asteroids in space
Computer animated asteroid impact
Meteors and Meteorites
• Meteors- pieces of rock
that burn up in our
atmosphere. (shooting
star)
• A meteor is the visible
streak of light that occurs
when a meteoroid enters
the Earth's atmosphere
• Meteorite- pieces of rock
that survive burning up in
our atmosphere and
land on the surface of
the Earth.
Meteor Shower
Meteorite
COMETS
• balls of ice and dust
in a specific orbit in
space.
• Kuiper Belt and Orrt
Clouds-these are
two areas at the
edge of our solar
system where
comets are located
until knocked into a
new, closer orbit
Halley’s Comet
(Every 76 years - 2062)
Kuiper belt
What if one hits us???
Asteroids and other objects come close to our planet EVERY
DAY! Most of the time we never notice them, but with improving
technologies we are detecting more of them, and detecting
them earlier.
In fact, on Wednesday Sept. 8th, 2010
NASA telescopes spotted 2 asteroids (both
around 30 feet in diameter) that came very
close to Earth. One actually passed
between the orbit of Earth and the Moon.
Neither would have been large enough to
cause large scale damage. The majority of
these asteroids would burn up while
entering our atmosphere.
-This blue ring is
the Oort cloud,
nearly a light year
away (to put it in
perspective)
-Sedna is the
furthest known
object to orbit our
sun. The IAU
(International
Astronomy Union)
has yet to define it
as a planet/dwarf
planet/asteroid.
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ONE LIGHT YEAR
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•
•
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10 trillion kilometres (1016 meters)
6 trillion miles
about 63,241.1 astronomical units
(One astronomical unit is the
distance from the Sun to the Earth.
It takes approximately 499 seconds
(8.32 minutes) for light to travel this
distance)