Transcript Astronomy ppt

ASTRONOMY
PG.715-721
“To infinity and beyond!”
-Buzz Lightyear
How Big Is The Universe?
 Journey To The Edge of The Universe ~10 min.
The Universe
 Houses all of existence
 From Largest to smallest you have:
Universe -> galaxy clusters -> galaxies -> stars
with planets (solar systems) -> stars (without
planets) -> individual planets (like Earth)
Size Representations
Galaxy Cluster
Individual Galaxy
The Milky Way Galaxy
-Where we live
Star Systems and Individual
Stars
Star with a solar system
-the star looks different here because
you are zoomed out to see the planets
Star (Hubble Telescope)
-close ups of individual stars
Brain Break
 1. What galaxy do we live in?
 2. When galaxies come together what do they
form?
 3. Do all stars have planets?
Creation of the Universe:
The Big Bang Theory
-States that the universe was a dense,
hot SUPER SIZED ball
-A violent explosion occurred flinging
material in all directions
Universe Expansion
pg. 720
 Galaxies move farther and farther apart from
each other
 Supports the Big Bang Theory
 As galaxies move farther apart from each other
space is created where it has never existed
before
 The universe is ACTUALLY GROWING in size
 Ex. Balloon
The Big Crunch
 Galaxies could stop moving apart
 Gravity would pull the galaxies back together
 Would create (or recreate) a high-density,
high-energy mass again
Will the Big Crunch happen?
 -Depends on the average density of the
universe
 If the density of the universe gets high
enough than gravity will pull more strongly
and pull all of the galaxies together
 If the density stays low than the universe
could expand FOREVER
Compare and Contrast
Big Bang Theory
Big Crunch
Star Getting Sucked into a
Black Hole
 http://www.youtube.com/
watch?v=ou3TukauccM
 http://www.youtube.com/
watch?v=D7s5X0NcLfc
Barycentre
Barycentre- the point between two objects where
they balance each other
Example: When the moon orbits Earth both bodies
are orbiting a central spot, the barycenter,
that lies between the two objects
-The same is true for Earth and Sun
-Even the solar system has
a barycentre
Kepler’s 3 Laws of Motion
 1. A planet doesn’t follow a perfect circle around the
sun, but an oval called an ellipse
 2. Planets follow an imaginary line. The farther away
a planet moves from the Sun the slower it moves .
The closer a planet is to the Sun the faster it moves
 3.The amount of time that it takes an object to orbit
the sun is proportional to it’s distance from the sun
Brain Break
 What is the force that would cause the Big
Crunch?
 What spot does Earth and Moon rotate
around?
 Which planet will take longer to orbit the sun,
why?
Motion of the Earth
 The Earth moves in several different ways in
space
 First it moves around the sun in a revolution
 Revolution- the motion of a body along a
path in space
 Earth also moves in a precession
 It wobbles like a top as it completes it’s revolution
around the Sun
 Takes 26
Earth Motion Continued
Earth also moves in a precession
 It wobbles like a top as it completes it’s revolution






around the Sun
Takes 26, 00 years to complete one precession
-the axis doesn’t change
The direction the North pole faces changes
Therefore, the stars that we can see change
The seasons change slightly
The wobble is very slow
Earth’s Motions
 The precession that Earth makes also
wobbles
 This wobbling of the precession is called
nutation
 Nutation is a wobble of 1/8 a degree
 Occurs over an 18 year period
 Is caused by the pull of the moon
Nutation
Universal Movement
 Our entire system is spinning and moving
towards the bright, giant Vega Star
 The Sun, like other stars, is revolving around
the galaxy which takes 230 million years
 The entire Milky Way Galaxy is spinning
towards the Andromeda Galaxy
Brain Break
 Draw pictures of the three different
movements that Earth makes
 1. Revolution
 2. Precession
 3. Nutation
Movement of the Earth in Space
 The earth revolves around the Sun
 It takes 365 days
 In 24 hours the earth makes one rotation
 The Earth tilts on it’s axis that creates the
seasons
 http://www.youtube.com/watch?v=hALtHnu4WE
o
The Earth and Seasons
 Each day the Earth makes one rotation
 Takes 24 hours
 one day
 Earth’s Seasons
 Caused by the tilt of the Earth
 The tilt is 23.5 degrees
 The side of the Earth that receives more sunlight
will have longer days and warmer temperatures
Earth’s Seasons Contd
 Earth’s seasons have NOTHING to do with the
distance from the Sun
 Earth’s Seasons Video
Earth’s Tides
 Tides- daily change in the elevation of the
ocean surface
 Caused by the gravitational pull on the Earth by the
moon
 Bay of Fundi, Nova Scotia
 How does it work?
 Two forces are at work, gravity and inertia
 Case of the Tides
Earth’s Tides
 Gravity- attracts the
moon and Earth
towards each other
 ***Remember the
moon is also pulling the
ENTIRE EARTH, not
just water – causes
nutation
 Inertia- the tendency
for objects to travel in a
straight line
 This keeps the Earth
and the moon from
crashing into each
other
 Inertia and gravity are
only balanced at the
center of the Earth
Earth’s Tides
 The side of Earth that is closer to the moon
has MORE gravity than inertia pulling on it
 The water, and Earth, are pulled towards the
moon creating a bulge of water on EITHER SIDE of
Earth
 As the Earth rotates and moon orbits the
water follows the pull of the moon
Video Explanations of Tides
 Earth’s Tides Explained
 NASA Model of Tides – turn to your neighbor
and explain what is happening in the video
clip
Brain Break
 What causes the tides?
 What two forces are responsible for the tides?
 Draw a DETAILED picture that explains how
the tides are created by the moon on Earth.
Tomorrow we will start watching:
Movie Clip