Download What is the universe???

WHERE IN THE
UNIVERSE ARE
WE???
The Heliocentric Model
• From 5,000 ago until
the 1500s, a
geocentric view of
planetary motion was
widely accepted
• Polish astronomer
Nicolas Copernicus
developed the first
heliocentric model in
which the planets
orbit the sun in circles
Problems with the
Geocentric Model
• Assumed that planets and stars orbited a stationary
Earth
• Could not explain the apparent retrograde motion of
some planets (Mars)
• Retrograde motion= planets further from the sun move
slower in their orbit due to less gravitational pull and
appear to move backwards
From Circles to Ellipses
• Danish astronomer Tycho
Brahe studied the
movement of Mars taking
nightly measurements
WITHOUT a telescope
• Accurately measured the
elliptical orbit within a
matter of degrees
• Died in 1602, seven years
before the telescope was
invented
Brahe’s Apprentice
• Johannes Kepler
(Brahe’s apprentice)
was in the right
place at the right
time and used
Brahe’s data to
proposed the first of
a set of three laws
that are named after
him
Kepler’s Laws
1. The planets move around the sun in ellipses
2. The imaginary lines connecting the sun to
each planet sweeps equal areas in equal time
3. The relationship between a planet’s ellipse
and its orbital period is: P2 = a3 (where P
equals the orbital period and a equals the
length of the semi-major axis)
Eccentricity
• Due to its elliptical orbit, a planet is not
at a constant distance from the Sun
• Perihelion = closest to
• Aphelion = farthest from
Kepler’s Second Law
Kepler’s Third Law
• The farther a satellite is from the object it is
revolving aroung:
1. The longer it will take to complete an orbit
2. The greater the distance it will travel to
complete the orbit
3. The slower its average speed of motion
Newton’s Laws
(physical science review!)
1. An object in motion tends to stay in
motion UNLESS an outside forces
acts upon it
2. An object accelerates in the same
direction of the force applied
3. For every action, there is a equal
and opposite reaction
Kepler + Newton
•Gravity pushes planets
towards the sun
•The gravitational
force holding the
planets on their orbit
is continuously
changing the planets’
velocity creating
elliptical orbits
•When planets are
closer to the sun, they
speed up!
Why does the night sky
change?
Parallax
• An apparent
change in the
direction of an
object, caused by
a change in
observational
position that
provides a new
line of sight.
Precession
• Earth’s wobble on its tilted
axis
• It takes the Earth about
26,000 years to wobble
• It is caused by a tug of war
on Earth by the Sun and
Moon, but the Moon’s pull
is stronger due to proximity
END OF
MOTION IN
SPACE NOTES
DAY 1!
Parts of the Universe
• Use the chart and
sticky labels provided
to organize the terms
on the right.
• When you think you
have the hierarchy,
raise your hand to be
checked!
•
•
•
•
•
•
•
•
•
•
•
•
•
Andromeda
Moons
Nebula
Milky Way
Big Bang
Galaxy
Local Cluster
Solar system
Planets
Sun
Star
Universe
Telescope
Where did our solar system
come from?
• Stars and planets form from interstellar
clouds (nebulae) of gas and dust, mostly
made up of hydrogen and helium
• We can see these all over the Milky Way
galaxy
• Clouds begin to condense when
gravitational pull of the matter in these
clouds grows stronger
• This is likely how our solar system came
to be
Where did our solar system
come from?
Where did our solar system
come from?
• Tiny condensed particles of matter from within
the interstellar cloud that started it all began to
clump and bind a few billion years ago
• As the diameters of these objects grew, they
became planetesimals
• As growth continued, some planetismals were
destroyed through meter collisions, but some
survived—and became the eight planets of our
solar system
• The third planetismal from the Sun became our
Earth
Where did our solar system
come from?
• Scientists theorize that the first planet to form
in our solar system was Jupiter, a gas giant and
the fifth planet from the Sun
• Jupiter kept growing larger and pulling
remaining dust and debris from space into its
orbit, as did the other gas giants
Where did our solar system
come from?
• This is likely why the
interior planets
(including us)
remained small and
rocky and (initially)
without any satellites
(moons)
• Some debris didn’t get
pulled into a
planetary orbit and
today makes up what
is commonly known as
an asteroid belt
(between Mars and
Jupiter)
What happened to the “extra”
matter?
• Some matter did not get
pulled into a planetary
orbit during the
formation of our solar
system
• Meteor= “space trash”
burnt up by our
mesosphere (shooting
star, satellite)
• Meteorite=“space trash”
that comes in contact
with Earth’s surface
What happened to the “extra”
matter?
• Comets= small, icy
bodies with highly
eccentric orbits around
the Sun
• Periodic comets=
repeatedly orbit in the
inner solar system
– Ex: Halley comet,
last seen in 1986,
expected again in
2061 (~75 year
period)
What is a Galaxy?
• Galaxy: Cluster or
bunch of billions
stars. There are about
100 billion galaxies in
the universe.
• Our neighboring
galaxy, Andromeda, is
2.5 million light years
from Earth!
• We belong to the local
group, a cluster of
about 35 galaxies.
What is a Galaxy?
What does the Milky Way look
like?
What does the Milky Way look
like?
Sagittarius A,
100
billion+
late main
sequence
and Red
Giant stars
make up
the disk,
suggesting
that this is
the oldest
part of the
galaxy
the mass in the
center of our
galaxy is about
2.6 million
times the mass
of the sun and it
believed to be a
super-massive
black hole that
“glows” because
of the hot gas
spiraling into it
The youngest stars in the
galaxy make up the spiral
arms, this is where most star
Edwin Hubble
• Born in small-town Missouri in 1889
• Attended high school in Chicago, excelling at
academics and athletics (broke state high jump
record, Varsity basketball player and boxer)
• Attended college on scholarship, continuing to play
sports and earned two degrees in mathematics and
astronomy
• Went to Oxford University Law School on a Rhodes
scholarship, where he did not continue his studies
in astronomy, but instead studied law.
• He quickly realized that he wasn’t satisfied
practicing law and went back to school for his
astronomy doctorate
Edwin Hubble
• As soon as he finished up his third degree, he was
drafted during WWI and didn’t begin his career as
an astronomer in California until 1917
• First person to…
– See other galaxies
– Develop a system to classify galaxies
– Explain redshifft
– Define the Big Bang Theory
• Hubble also refined Einstein’s theory of
relativity and the two famous scientists got
together in 1931 because Einstein was
grateful for Hubble correcting his mistakes
How do we know the universe
is expanding?
• Edwin Hubble
discovered that
most galaxies have
redshift in their
spectra
• Redshift of an
object in space
depends on distance
from Earth
• The farther away an
object is, the faster
it is moving away
How does the night sky tell us
about the past?
• Because many
galaxies are so
distant, it takes a
long time for their
light to reach Earth
• Ex: When we see
sunlight, we are
really seeing light
the Sun produced
eight minutes
before
Models of the Universe
• Steady State Theory
• Big Bang Theory
(Fred Hoyle): New
(Edwin Hubble):
matter has been
The universe began
created such that
as a point and has
when objects in
been expanding
space move, new
ever since
objects fill that void
• NOT really an
• Conflicts with the
explosion, but an
law of conservation
expansion
of matter
Big Bang v. Steady State
Which theory is right?
• BOTH theories have observational tests to support
them
• BUT evidence weighs in favor of the Big Bang
• If the universe began as a highly compressed point (as
stated by Big Bang), then high temperature and
pressure would have created a great deal of high
energy radiation
• In 1965, scientists discovered persistent background
noise in radio antenna caused by weak radiation
• This is believed to be remnant of the Big Bang, as the
energy has shifted over time
• Steady State supporters have no explanation of this
What is going to happen to
our universe?
1) Closed Universe (Big Crunch)—
expansion will stop and shift to
contraction
2) Open Universe—expansion will
continue forever
3) Flat Universe (Big Chill)—expansion
will slow to a halt in an infinite
amount of time, but never contract
What is going to happen to
our universe?
What is going to happen to
our universe?
• The constant interaction between gravity
(pressure in) and expansion (pressure out) will
determine what happens
• One approach to determining the fate of the
universe is to measure how much expansion has
already slowed, using redshift of distant galaxies
• Latest evidence: expansion has started to speed
up again! We don’t know what’s causing it!!
• Most evidence points to a flat universe
(inflationary model)
END OF
DAY 2
NOTES!!
Big Bang Balloon Quick Lab
• Use a felt-tip pen/marker to make 5 dots
in a row, 1 cm apart, on your balloon 
Label one “Earth” and the others A-D
(these represent other galaxies)
• Partially inflate the balloon (1-2 big
breaths) and hold it…do not tie it! Use a
piece of yarn to measure the distances at
time 1, convert to centimeters using your
ruler, and record
• Repeat for time 2 and 3, then answer
analysis questions
Set up a table like this…
POINT
A
B
C
D
Distance 1
Distance 2
Distance 3
Distance 4
Hubble’s Law
• Blow up your balloon just a little
(don’t tie it!). Now measure the
distance from Earth to each dot
again
• Inflate the balloon a little more and
repeat measurements.
• Now fully inflate the balloon and tie
it. Complete your final
measurements.
Analyze & Conclude Questions
1) Are the dots still separated from each other by
equal distances?
• Which dot moved the greatest distance? The least
distance?
• How would your results change if you had
measured distances from dot D instead?
• Which of the three proposed models of universal
expansion would be best modeled by your
balloon? Explain.
Our Motion & the Moon
Nutation
Barycenter
What makes our Moon weird?
• Large in comparison to the
planet that it orbits
–27% the radius of Earth
• Great distance from Earth (most
moons are closer)
• Solid rocky composition (most
are icy)
Moon Vs. Earth
Differences
• The moon can get
reallllllly hot and cold
(127°C, -173°C), but
because it has no
atmosphere, it does
not retain heat in the
absence of sunlight
• No erosion (no wind
or water)
Similarities
• Areas of high
elevation (highlands)
and low elevations
(maria and craters)
• Very similar mineral
content
How was the Moon formed?
• Capture Theory: As the solar system was
forming, an object came too close to the forming
Earth and got sucked into our gravitational pull
• Simultaneous Formation Theory: The moon
and Earth formed at the same time and in the
same area (that’s why the compositions are
similar)
• Impact Theory: The moon formed as a result
of the collision of Earth and a Mars-sized object
about 4.5 billion years ago. Debris from both
merged together to form the moon (most widely
accepted!)
Moon Phases: Oreo Lab
1. Separate your cookies carefully, so that ½ of the
cookie has ALL of the frosting and the other ½ of the
cookie has NO frosting.
2. Use your plastic butter knife to scrape off the frosting
from the first cookie, making a shape of the waxing
crescent.
3. You will continue using the butter knife to scrape off
the frosting for each of the moon phases. (How will
you represent new moon?)
4. Place the cookies in order on a paper plate and
LABEL them correctly. Use chocolate frosting as
“glue”.
5. Don’t forget to add Earth to your model!
As, you finish, you should begin work on Study Guide
28.3 (p. 180-182)
The difference between…
Rotation
• Spinning of the
earth around it’s
axis
• Period: 24 hours
• Creates day and
night and time
differences
Revolution
• Movement of the
earth around the sun
• Period: 1 year
• In the elliptical orbit,
sometimes different
parts of the planet are
closer to/farther from
the sun
• Gives us seasons
Earth is tilted!
What is a solstice?
SUMMER SOLSTICE
• Sun is directly over
the Tropic of Cancer
at 23.5° N
• The Northern
hemisphere has its
longest days
• The Southern
hemisphere has its
shortest days
WINTER SOLSTICE
• Sun is directly over
the Tropic of
Capricorn at 23.5° S
• The Southern
hemisphere has its
longest days
• The Northern
hemisphere has its
shortest days
What is an equinox?
• Equi = equal
Nox = night
• Happens twice a year in the autumn
and spring
• The lengths of the day and night for
both hemispheres is the same
Earth’s Tilt and Climate Change
• The Earth wobbles in space so that it’s tilt
changes about 25 degrees…every 41,000 years
• Change in tilt = Change in intensity of seasons
• When spring/summer is milder, ice and snow
don’t melt
• When there is more ice and snow on the earth, it
reflects sunlight instead of absorbing it and it
gets even colder
• Carbon dioxide levels fall as ice sheets grow
• The last ice age was about 10,000 years ago