G9 Science Q3- Week 8-9- Constellation.ppt

Constellations
& Stars
PREPARED BY: TYPE YOUR NAME HERE

Show which
constellations may
be observed at
different times of
the year using
models
S9ES -IIIj - 35

I. Constellations
 Group of stars that
appear to form a
pattern in the sky.
 88 recognized by
International
Astronomy Union

A. Zodiac
 Band of 12 constellations along
the ecliptic.

B. Ecliptic
• The plane of the Earth’s orbit
around the sun
• The apparent path that the sun
(and planets) appear to move
along against the star
background.

C. Circumpolar
Constellations
 Can be seen all year long
 Never fully set below the horizon
 Appear to move counter clockwise
around Polaris
 Caused by Earth’s Rotation

Examples of Circumpolar
Constellations
1.Ursa Major – The Big Bear
2.Ursa Minor – The Little Bear
3.Cassiopeia – Queen on Her
Throne
4.Draco- The Dragon
5.Cepheus- The King

 # of stars seen as circumpolar depends
on the observers latitude
 Further North the observer lives, the
more stars will appear circumpolar
 Earth turns west to east
 Sky appears to turn east to west

D. Ursa Major
 Best known constellation
 Common name is Big Dipper
 Pointer stars- front 2 stars of the Big
Dipper which point to Polaris (North
Star)

II. Seasonal Changes in
Constellations
 Big Dipper
 In Fall: Low over northern horizon
 Spring: High overhead
 Cassiopeia
 In Fall: Straight overhead
 Spring: Low over northern horizon

Seasonal Change &
Nightly change of the
Dippers

III. Summer
Constellations
• 1st
3 bright stars that rise form the
Summer Triangle
Summer Triangle
1. Vega- in Lyra the Harp
2. Altair- in Aquilla the Eagle
3. Deneb – in Cygnus the Swan (Northern
Cross)

IV. Most Famous Winter
Contellation
 Orion Contains:
1. Betelgeuse (Bet el
jooz) a bright red
super giant star found
forming Orion’s right
shoulder
2. Rigel – a blue super
giant: 7th
brightest star
in the nighttime sky

G9 Science Q3- Week 8-9- Constellation.ppt

3 Stars of Orion’s Belt
 Can be used to find 2 other
constellations & a star
cluster
1. Canis Major- (Big Dog)
follow the line made by
the 3 stars of Orion’s
belt down to the left
–Sirius- the brightest star in the
nighttime sky is found in Canis Major

2. Taurus (the Bull)
 Follow the line made by Orion’s belt up
& to the right
 Aldebaran- Red star that is the eye of
the bull is the 13th
brightest in the
nighttime sky

3. Pleiades Star Cluster
(7 sisters)
 Follow the line made by Orion’s belt
up to the right, go through Taurus to
a clump of stars to the right.
 Called Subaru in Japan – means
“Unite”

V. Kinds of Stars
A. Red Giant - large red star
at least 10x diameter of
the sun
 Old Stars
 Ex. Aldebaran
 The sun will swell
into a Red Giant
when it is old

B. Super Giant
 Largest of all stars 100x more
luminous
 Explode as a Super Nova
 Can form Black Holes
 Ex. Betelgeuse, Rigel, Polaris

C. Dwarf Stars
1. Less luminous
2. Very dense, mostly carbon
3. Tightly packed nuclei
4. Remains of a red giant that ran out of fuel
5. 1 cup full of star =20 tons or 5 elephants.
6. Most are red/orange/yellow
7. White dwarf is the exception to the color
8. Sun is a yellow dwarf

Size Comparison of
Various Stars

VI. Variable Stars
 Change in brightness over regular
periods of time
 Ex. Cepheid Variables/Pulsating Stars
Binary Stars & Eclipsing Binary Stars

A. Cepheid Variables/
Pulsating Stars
 Change in brightness as they expand &
contract
 Unequal balance between gravity &
nuclear fusion
 Ex. Polaris, Betelgeuse

B. Binary Star Systems
 Two stars of unequal brightness
revolving around a center point
 Ex. Algol & its companion star in
Perseus

C. Eclipsing Binary
Stars
 Two close stars that appear to be a
single star varying in brightness.
 The variation in brightness is due to
one star moving in front of or behind
the other star.
Occurs because we see
the system on edge
instead of from above or
below

VII. Pulsars or Neutron
stars
A. Discovered in 1967 (LGM)
B. A distant heavenly object that emits
rapid pulses of light & radio waves
C. Formed when a Super Giant collapses;
Protons & Electrons are forced so close
together that they fuse and form only
neutrons

Twinkle Twinkle Little
Star
"Twinkling Stars" are due
to Earth's atmosphere

VIII. Life Cycle of a
Medium Mass Star
1. Nebula
2. Protostar
3. New/Stable State Star
4. Red Giant
5. Planetary Nebula
6. White Dwarf
7. Black Dwarf

1. Nebulae (Plural of
Nebula)
 Space gas seen as faint glowing clouds
 Mostly hydrogen
 Star dust is extremely small, smaller
than a particle of smoke & widely
separated, with more than 300
ft. between individual particles.
 Nebulae still hinder star gazing because
they absorb light which passes through
them.

Types of Nebulae
 Diffuse Nebula - gases glow from stars
w/in them
Ex. Nebula
found in
Sagittarius

Types of Nebulae
 Dark Nebula -
nebula not near a
bright star
 Ex. Horse Head
Nebula in Orion

2. Protostar
 Shrinking gas balls, caused by a swirl of
gas forming dense areas.
 The gravity of the dense swirl in turn
attracts nearby gases so a ball forms.
 Nuclear fusion occurs & Helium is
formed from Hydrogen
 A new star is born in our galaxy every 18
days

3. Stable State Star
 Star that releases energy in enough
force to counter balance gravity
 Star stops contracting
 Also known as a main sequence star
 Ex. Sun

4. Planetary Nebula
 The outer layers of the Red Giant puff
out more and more.
 The star loses gravitational hold on its
outer layers and they get pushed away
by the pressure exerted from solar
winds

5. White Dwarf
 Fuel is used up
 No nuclear fusion
occurring
 Remaining heat
radiates into space

IX. Life Cycle of a Massive
Star
1. 1st three steps are similar
2. Super Giant
3. Super Nova
4. Neutron Star / Pulsar
5. Black Hole

1. Super Giant
 Rare stars, largest of all
 100x more luminous
 Only stars with a lot of mass can
become super giants
 Some are almost as large as our entire
solar system
 Ex. Betelgeuse & Rigel

2. Super Nova
 Explosion from a massive Super Giant
 Outer layer blasts away at end of Life
Cycle
 Emits light, heat, X-rays, & neutrinos
 Leaves behind a neutron
star or black hole

3. Neutron Star/ Pulsar
 The remains of a super nova
 Very small, super-dense star which is
composed mostly of tightly-packed
neutrons
 Rapidly spinning leftovers of a star
 Emits energy in pulses

4. Black Hole
 Occurs when a star's
remaining mass is
greater than three
times the mass
of the Sun
 Star contracts tremendously
 Incredibly dense with a gravitational field
so strong that even light cannot escape.

X. Distance to stars
A. The Sun is closest star to Earth
B. Takes light 8 minutes to reach Earth
C. Avg. distance:150,000,000Km = 1
AU distance from Earth to the Sun
D. Next nearest star is Proxima
Centauri 4.2 light years away; it can
only be seen in the southern
hemisphere

E. Light year
• The distance light has traveled in
a year
• 9.5 x 1012
Km/yr
• Speed of light 300,000 Km /sec

XI. Physical Properties of
Stars
A. Nuclear fusion supplies the
energy for stars
 Huge size & mass of a star means
outer layers press inward w/
tremendous pressure
 Hydrogen ignites
 Star becomes a huge nuclear bomb
 Hydrogen nuclei combine to form
Helium

B. Color of star depends on
surface temp.
1. Blue - hottest stars
Ex. Rigel in Orion; Vega in Lyra;
Sirius in Canis Major
2. Yellow - medium stars ex. Sun
3. Red - coolest stars
Ex. Betelgeuse in Orion, Antares
the heart of Scorpio, Aldebaran in
Taurus

C. Star size
-Varies, large range
Smallest can be
smaller than Earth
Largest may be 600,000,000 x
Earth.

D. The Sun
• is an average star
• yellow in color
• 300,000 x the
mass of Earth

XII. Luminosity
 Brightness of a star
 Depends on size & temperature
 Hertzsprung-Russell Diagram graphs
Absolute Magnitude (or Luminosity) vs.
Temperature of stars
 Shows the life cycle of stars

A. Absolute Magnitude
• Measure of the amount of light it actually
gives off if all stars were placed a distance
of 32.6 light years away
• Lower # means brighter star
• Negative #’s are the brightest
• Ex. Sun = 4.75 Sirius = 1.4 Rigel = –7.0
Rigel’s the Brightest of the 3 listed if all were
lined up next to each other.

B. Apparent Magnitude
 A measure of the amount of light received on
Earth
 Stars below 0 are brightest
 Each magnitude differs by 2.5
 1st
magnitude is 100 x brighter than 6th
magnitude
 Ex. Sun = – 26.8 Sirius = – 1.45
Full Moon –12 .6 Rigel = .11
 Sun is the brightest in our sky.

XIII. Galaxies
 Systems containing millions or billions
of stars, gas, & dust held together by
gravity
Ex. Milky Way
 There are great distances between
galaxies
 The Milky Way belongs to a group or
cluster of galaxies called the local
group

Spiral Galaxy Like the
Milky Way

Three major classes of
galaxies:
1. Elliptical - shaped like large
ovals or football shape
2. Spiral - pinwheel shaped; our
sun is on a spiral arm of the
Milky Way
3. Irregular - many different
shapes that aren't like the other
two

XIV. Quasar
 Quasi stellar radio source
 Galaxies, very far away, with bright centers
 Thought to have a super massive black hole
at center
 Most luminous objects known to man

XV. Electromagnetic
Spectrum
 The arrangement of electromagnetic
radiation from Radio waves to Gamma
waves

Stars Emit:
1. Visible light
2. X-rays
3. Radio waves
4. Infrared waves
5. Ultraviolet waves

Venus & Saturn by E-
spectrum
Ultra violet Visible Infrared Radio
Ultra violet Visible Infrared Radio

X-ray & Ultra Violet Image
of Sun

Visible, Infrared & Radio
Images of Sun

A. Electromagnetic
waves:
 Differ in wavelength & frequency
 All electromagnetic waves travel at the
speed of light; 300,000 km/sec

 a has a longer wavelength (distance
from one crest to another) but lower
frequency ( # of waves that pass by a
point in a second)

 b has a shorter wavelength but a higher
frequency

B.
Spectroscope
 Instrument that separates
light into its colors.
 Contains:
 Prism at one end
 Slit at opposite end which
lines up with the light source

C. 3 Types of Spectra
1. Continuous Spectrum
2. Brightline Spectrum
3. Darkline Spectrum

1. Continuous Spectrum
 Produced by a glowing solid
 Example a Tungsten white light bulb, &
white sunlight.

Continuous Spectrum
Cont’
 Continuous set of emission lines
forming an unbroken band of colors
from red to violet.
 Shows the source is sending out light
of all visible wavelengths.

Visible Spectrum
 ROY G BIV
 All the colors of
the rainbow
 A continuous
spectrum
red orange yellow green blue indigo violet

2. Dark-Line Spectrum /
Absorption Spectrum
 Produced when a cooler gas lies
between the observer and an object
emitting a continuous spectrum
 Example:
1. The atmosphere of planets
2.Outer layers of a star

Absorption Spectrum Cont’
 The cooler gas absorbs specific
wavelengths of radiation passing
through it.
 This spectrum appears as a continuous
spectrum of all colors with a number of
gaps or dark lines throughout it.

3. Bright-Line Spectrum /
Emission Spectrum
 Produced by a glowing gas which
radiates energy at specific wavelengths
characteristic of the element or
elements composing the gas
 Example Neon signs, black lights, LED’s

Emission Spectrum Cont’
 This spectrum consists of a number of
bright lines against a dark background.
 Each elements has its own distinctive
spectra much like a fingerprint
http://jersey.uoregon.edu/vlab/elements/Elements.html

XVI. The Doppler Effect
 as sound approaches the wavelength is
compressed so the pitch is higher
 as sound leaves the wavelength is
stretched out so the pitch is lower
 The same thing happens with light

Red Shift
 If a star is moving away from Earth
there is a red shift, of its line spectra; if
the star is moving toward the Earth
there is a blue shift of its line spectra

Red Shift
 Red shift is evidence the universe is
expanding.

 Content, images, text, etc. used belong to the rightful
owner. No copyright infringement intended.

G9 Science Q3- Week 8-9- Constellation.ppt

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