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Astronomy

8th grade science
by

Natosha Daniels

on 26 March 2015

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Transcript of Astronomy

the Universe
N. Daniels 2012
Waves and the
Electromagnetic
Spectrum
What does this have to do with science?
Thermograms (used in the ghosthunter's video) use infrared rays to detect heat differences. Warmer matter gives off higher energy infrared rays than cooler matter.
Use the youtube videos and links to fill in the notes on the Electromagnetic Spectrum. (Due by the end of class)
Transverse Waves
•Energy movement is
perpendicular
to the direction in which the wave travels.
Amplitude
- the distance from the
crest to the resting position
Wavelength
- distance from
crest to crest
.
Frequency
- number of waves in a given amount of time. Measured in
Hertz
. 1 Hz is equal to 1 wave per second.
Electromagnetic Spectrum: Waves that can travel through empty space
resting position
highest point of a transverse wave
lowest point of a transverse wave
The Tecnical Definition: A wave is a repeating disturbance or movement that transfers energy through matter or space

Wave
- a way that energy is transported. some waves require a
medium
, while others (EM Waves) do not.
What is a wave??????
Two types of waves:
Transverse and Logitudinal
Longitudinal wave
Longitudinal wave
- movement (or oscillation) is
parallel
to the direction in which the wave travels.
Compressions
-where the wave is
closer
together
rarefaction
-where the wave is
further apart
.
Examples: Sound Waves and seismic waves called P-waves.
moves parallel to energy
energymoves up and down
pushes the wave forward.
Em Waves are classified by their
wavelength, or energy.

Which waves have the shortest wavelength, or the most energy?

Which waves have the longest wavelength or the least energy?

The only part of the EM Spectrum we can see is the
visible spectrum
.
The EM Spectrum
The Hertzsprung-Russell Diagram
This is a graph that shows the
differences and relationships between stars.
Horizontal
(x) axis
- star’s surface
temperature
. The axis is reversed from the way you normally see a graph.
Vertical
(y) axis
- Star’s
luminosity or brightness
(Absolute magnitude-actual brightness without the atmosphere's effect on the star)
The sun is a main sequence star
located in the middle of the diagram.
The Sun is medium sized compared to other stars.

Nuclear fusion converts hydrogen to helium producing energy.

The Sun is many thousands of times closer to the Earth than any other star.
http://sunshine.chpc.utah.edu/labs/star_life/support/HR_static_real.html
What color would a very bright, very hot star be?
True or False
The sun is a medium star. Average brightness, average temperature.
What is a star?
How is a star born?
Is the sun a star?
Are all stars the same?
Spiral
Elliptical
Irregular
Galaxies
-Are large scale groups of stars that are bound together by gravity. They also contain gases and dust

From the Greek word Galaxias meaning milky (from the Milky Way).
Galaxies are classified into 3 groups, based on their shape:
Have a
nucleus
, or center, of bright stars.
Outward from the center are
flattened

arms
of stars that spiral around the nucleus.
The
spirals
contain millions of
young stars, gas & dust.
Some spiral galaxies have a bar running through them. Known as a
Barred spiral galaxy
.
Have shapes that range from nearly
spherical
to a flattened
disk.
Have very
bright
centers.
Do
not
possess
spiral arm
s.
Do
not
have
young stars
and contain very
little dust
and
gas
.
Have no particular
shape
. Tend to be
smaller
and
fainter
than other galaxies.
Could be formed from the
collision
of two different galaxies.
Stars are of
low mass
and
cannot organize
into a pattern.
Irregular galaxies are
unevenly distributed
throughout the universe
Galaxies
Size of a typical galaxy is
100,000 light years
in diameter.
Converts H to He
All stars are huge spheres of glowing gas
Stars begin in a huge collection of gas and dust called a nebula
As GRAVITATIONAL FORCES increase, H is converted into He and the star shines
Every second, the sun converts 400 million tons of hydrogen into helium.
There are at least
100 billion
galaxies
Each galaxy contains on average,
100 billion stars
Multiply 100 billion times 100 billion for the number of stars
Brain Break
No, size matters!
Big stars are hot, blue, and die young
Small stars are cool, red, and live long
Medium stars, like our sun, are yellow and last 10 billion years
We are born with 350 bones but we die with _______ bones.
206
Brain Break
The nearest one is the Sun (appx
8 light minutes
away) Alpha Centauri, the Sun's closest neighbor is 4.3 light years.
A
light year is the distance light travels in 1 year, or 9.5 x 1015 meters
How Far Away Are the Stars?
When massive stars die, they explode
They make heavy elements when they do
They become either neutron stars or black holes after blowing up
Supernovas
Black Holes
A place where a star once was
A place where light cannot escape
A possible gateway to another time and place
A huge x-ray source
Most stars become one of these in their old age
Stars that run out of hydrogen, start fusing helium onto carbon
They get big and bright, but are cool
Red Giant
How will our sun die?
5 billion years from now, our sun will become a bloated red giant
The earth will get swallowed up and vaporized
Brain Break
STARS
The Bird' - albeit it also bears resemblance with a cosmic Tinker Bell - is composed of two massive spiral galaxies and a third irregular galaxy,
What makes up the universe?
Nebula
-collection of
gasses and dust
(pre-starlike dude.)
Meteoroid
-
rocks
in space
Meteor-when a meteoroid enters earths
atomosphere
Comets
-
icy
body that releases gas or dust. Has a
nucleus and a coma
.
Asteroids
- small planetary bodies that revolve around the
sun
.
Most asteroids are in the asteroid belt between the orbits of
Mars and Jupiter
H.R. Diagram
waves
Where did all of this come from?
Good question
The
Big Bang
, perhaps
12
billion years ago the whole universe was in a space the size of a head of a
pin
and
blew
itself up!
Believe what you want
The
red shift
evidence supports it
Cosmic background
radiation
supports
It might
slow down
, fall back on itself, and start a new
Big Bang
It might expand
forever
, become cold, dark, and
die
How will It End?
Who knows?

Maybe there are a trillion universes

Maybe this is it

Any more questions?
What was before the Big Bang?
All the galaxies are flying
apart
The universe is
expanding
Black Holes
The Universe
Brain Break
Medium-something a wave travels through. Like how sound waves travel through air or how you can feel the vibration when you hit your desks.
The following videos are here for more information. These are not a part of class notes. You may watch these for information on your project and/or personal knowledge base.
http://www.youtube.com/watch?v=TnpTcrtsN3U&playnext=1&list=PLEB868806440966E3&feature=results_main
http://www.pbs.org/wgbh/nova/physics/doppler-effect.html
Click here to answer questions
Why is this important?
Stars give off EM waves at the speed of light. We can use this to measure distances
(light years)
. We can also tell which elements are in stars by the color it gives off
(spectral analysis)

Stars that are moving away from us give off a

RED

light because the wavelength has

INCREASED
.

Stars that are moving toward us give off a BLUE light be cause the wavelength in

DECREASING.

From this discovery, scientists began to accept that the Universe is expanding. Scientists now believe that the Universe began to expand
from a single point in space some 13.7 billion years ago—the
“Big Bang Theory.”
In the late 1920s, astronomers Georges
Lemaitre and Edwin Hubble separately proposed that all distant galaxies are moving away from Earth (red-shifted)
and that the further away a galaxy was, the
faster it was moving.
the hotter the surface temperature, the
brighter the star.
Full transcript