Stars, Galaxies, and the Universe

1
Chapter 3 "Stars, Galaxies, and the Universe"
2
Constellations
They are based in myth from ancient cultures.
A group of stars that appear to form a shape
There are 5 constellations we see year round.
They are called the Circumpolar constellations
3
These constellations are around the North Star,
or Polaris.
The five Circumpolar Constellations are
Draco
Ursa Minor
Cepheus
Cassiopeia
Ursa Major
4
The main stars are Eltanin and Thuban.
To find Draco Locate the big and little
dippers. Dracos tail runs between them.
The constellation represents the snake Ladon,
which Hera, Zeus' wife, put to keep guard over
her golden apples in the Hesperides garden. It
was killed by Hercules during his eleventh labor
5
The two main stars are called Caph and Schedar.
To locate Cassiopeia find Cepheus. On one side
is Draco, and on the other is Cassiopeia. She
looks like the letter W in the night sky.
The Romans described her chained to her throne
in the heavens as punishment for her
boastfulness. As the sky appears to rotate, she
can sometimes be seen suffering as she hangs
upside down
6
The main star located in Cepheus is Alderamin.
Cepheus was the king of ancient Ethiopia. He was
married to Cassiopeia, and together they had a
daughter, Andromeda.
To locate Cepheus find Polaris (North Star), and
Cepheuss peak will be nearby.
7
According to some Native American legends, the
bowl of the Big Dipper is a giant bear and the
stars of the handle are three warriors chasing
it. The constellation is low in the sky in autumn
evening sky,so it was said that the hunters had
injured the bear and its blood caused the trees
to change color to red.
The Big Bear is also known as The drinking
gourd, or the plow or cart.
The main stars in Ursa major are Mizar, and
Merak,
To locate Ursa Major find the asterism known
as the big dipper. That is part of Ursa major.
8
Ursa Minor is an important constellation, because
it contains Polaris (the North Star). Other
stars include Kochab, Yilden, and Pherked.
There are 7 stars in Ursa Minor
The history of Ursa Minor (or the Little Bear ,
also called the Hippopotamus, or crocodile)
revolves around the birth of Zeus, and the fact
that his father, having believed in a prediction
that one of his children would dethrone him,
wanted to do away with him. The two bears
protected baby Zeus, who did go on to dethrone
his father.
To locate Ursa minor, find the North Star or the
asterism the little dipper.
9
Telescopes
Radio
Infrared
Visual
X-ray
Gamma
The Milky Way in different forms
10
The First thing you need to realize is that the
electromagnetic spectrum is a series of waves.
As you decrease the wavelength you get different
properties.
11
Visible light
The light you see with your eyes.
Electromagnetic radiation
Energy that can travel directly through space in
the form of waves.
Light is a form of this.
Wavelength
Spectrum
The distance between the crest of one wave and
the crest of the next wave.
A range of different colors with different
wavelengths. Rainbow colors
The electromagnetic spectrum includes radio
waves, infrared radiation, visible light, uv
radiation, X-rays, and gamma rays.
12
Refracting telescope
A telescope that uses two lenses to gather and
focus light onto a small area.
Convex lens a piece of transparent glass that is
curved and thicker in the middle than at the
edges.
13
Reflecting telescope
A telescope that uses two mirrors to gather light
and a convex lens to focus.
14
Which is Which?
15
Light Path for Refracting Telescope
16
Radio telescope
Collects radio waves from space, and appears like
a satellite dish. Usually found in groups called
arrays.
17
X-Ray telescope
This telescope is much like a reflecting
telescope BUT, the mirrors are coated with gold
and x-rays are reflected off them.
18
Gamma Ray telescope
Uses Gamma rays emitted by objects in space to
gather images of the object.
19
Infrared Telescope
Telescope that uses infrared radiation from
objects in space to produce an image.
20
Hubble Space Telescope
A telescope that was put into orbit around the
Earth in 1991. It is a reflecting telescope,
that aids our view of the universe, because it is
above our atmosphere. It also uses Ultraviolet
and infrared radiation.
Why is it helpful for the telescope to be above
our atmosphere?
21
Pictures Taken From The Hubble
22
Observatory
A building that contains one or more telescopes.
Most are located on mountaintops. Why?
Mauna Kea in Hawaii is probably the best
observatory location. It is 4,200 meters above
sea level.
Visible light telescopes require scientists to
stay awake all night. Why?
Radio telescopes can be used 24 hours a day.
23
Galaxy
A large system of swirling gases, dust, stars,
planets, and moons. They may be millions of
light years across.
24
Universe
Everything that we know of or could discover.
25
Stars, Stars, Stars
The distance that light travels in a year. This
is how scientists measure distances to stars.
Light Year
How fast does light travel?
300,000 km/sec or 186,000 miles/sec
This means that if I shine a spotlight toward
California, the light would race back and forth
31 times in 1 sec. Wow! Thats fast!
9.5 million million kilometers or
5,865,696,000,000 miles
How far can light travel in a year?
Thats equal to 977,616,000 round trip flights to
California!!
26
The brightness of a star as seen from Earth.
Apparent magnitude
The problem with this is that the stars that are
close to us, all appear very bright, but are they
really brighter than all of the other stars?
The brightness a star would have if it were a
standard distance from the Earth.
Absolute magnitude
This is a more precise way to tell if one star is
actually brighter than another star.
A graph that shows stars temperature versus
brightness. The plotted points formed a pattern.
H-R diagram
This graph was designed by two scientists named
Ejnar Hertzsprung and Henry Norris Russell, hence
the name H-R.
27
Stars
28
Stars
29
Stars
30
Stars
31
Life Cycle of a Star
Nebula
A huge swirling cloud of dust and gas.
Witchs head nebula
Cats eye nebula
The earliest stage of a stars life. Gravity
pulls the gas and dust together. A star is born
when nuclear fusion starts.
Protostar
Main sequence star
A star that is going through nuclear reactions to
form heat and light. This is what our sun is.
32
Death of Stars
How long a star lasts depends on how much mass it
has.
Our sun is about halfway through its life cycle.
Red Giant Stage
The inner core shrinks, and the outer part
expands.
Betelgeuse a red super giant.
White Dwarf Star Could also be black or brown
The star is out of fuel. The outer layer drifted
away, leaving only the core.
33
A star explodes and huge amounts of energy are
released.
Supernova
The material released can be recycled to form new
nebulae.
A star that has contracted . Gravity is so
intense, that nothing can escape it.
Black Hole
This is what happens to the most massive stars.
34
Neutron stars
A type of star formed from material left behind
after a supernova.
These are smaller denser than white dwarfs.
They may have 3x the mass of our sun, but only
measure 20 miles across!
35
Stars
36
Stars
37
Stars
38
Stars
39
Stars
40
Stars
41
Stars
42
Stars
Protostar
43
We can learn many things about galaxies using
scientific equipment including
Distance, Size, Luminosity, Mass and Motion
There are three main types of galaxies Spiral E
lliptical Irregular
44
Spiral galaxy --gt these galaxies have arms that
curve outward from a central area.
Our galaxy, the Milky Way, is this type!
Our galaxy is larger and more massive than the
average galaxy.
Galaxies are put into groups called Clusters.
Our cluster is called the Local Group. There
are about two dozen (24-25) galaxies of various
sizes and shapes.
45
Elliptical galaxy --gt a galaxy that is a 3-D
football shape.
This is the most common shape for a galaxy.
Almost 70 of galaxies are this type.
Some of the galaxies are very small, while others
are larger than our local group (which contains
24 galaxies!!)
46
Irregular galaxy --gt These galaxies do not fit
into either of the other categories. Any shape
other than spiral or elliptical fits into this
grouping.
47
BIG BANG THEORY
A theory concerning how the universe began- With
an explosion.
48
(No Transcript)
49
(No Transcript)