Transcript Space - Mr. Birrell

Space
Part One
The Origin and Evolution of the Universe
What do we know about space?
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•
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What is it?
Where is it?
What’s in it?
Is everything important?
1.1 What’s Important?
Gravity
• An attractive force that pulls things together
Why don’t people on the other side of the earth
fall into space?
• Because they are attracted towards the centre
of the earth by gravity
• Any two objects with mass experience a
gravitational attraction towards each other
Top Five
Complete the Top Five assignment with a
partner!
• Found on Mr. Birrell’s website
http://mrbirrell.wikispaces.com
Planets
• From Greek meaning “wandering star”
• Smaller than stars and do not emit light
• Two types:
– Large, low-denisty gas giants
– Smaller, rocky terrestials
• First confirmed discovery of a planet outside of our
solar system came in 1995
Planets in our
solar system
http://www.aerospaceweb.org/question/astron
omy/solar-system/planets.jpg
Mars Surface
Mar Sunset Video
Nasa.gov
Stars
• Start as huge clouds of dust and gas called
“nebulas”
• As the clumps swirl and bump into each other,
they get larger, and their gravitational force
gets stronger
• Eventually the clumps are dense and hot
enough for nuclear fission to start
– Now called a star
Nasa.gov
Types to know:
• Red Giant
– The size of our sun or smaller
• Red Supergiant
– 10 times or more larger than our sun
• White Dwarf
– After a star is dying, it shrinks in size and becomes
hotter
Other terms:
• Supernova
– An enormous explosion at the end of a star’s life
– Star has used up its fuels to keep nuclear fission
going
– Core collapses to become either a neutron star or
a black hole
– Shock waves cause the outer layers to explode
outward in a rapidly expanding nebula
– Only one has been seen with the naked eye
Planetary Systems
• A group of objects including at least one
planet orbiting around a star
• Our solar system is an example
Galaxies
• Made up of billions of stars, planetary
systems, gas and dust, held together by
gravity.
• The galaxy that our solar system is located is
called the Milky Way Galaxy. If you could
travel at the speed of light, you could travel
from one side of the Milky Way Galaxy to the
other side in 100,000 years.
Andromeda (our nearest neighbour)
Humans vs. Galaxies
What is the greater number: the number of cells
in your body or the number of stars in a galaxy?
Typical galaxy: ~400 billion (400000000000)
Cells in body: ~75 trillion (75000000000000)
Largest galaxy known: ~100 trillion
Clusters of Galaxies
• Groups of galaxies held together by their
mutual gravitational force
• Largest known gravitational bound objects
• Typically contain 50 to 1000 galaxies
• The Milky Way is in a cluster of about 40
galaxies
Galaxy Cluster ACO 3341
The Universe
• Everything that exists, including matter and
energy everywhere
1.2 Space is Big
How big is it?
Really
BIG
Question: How long would you survive if you
were ejected into outer space?
Powers of Ten
Scales of very large things and very small things
are tough to visualize.
“Powers of Ten” by IBM helps.
Special Heliocentric Illustration Tissue
Demonstration
Quick, to the hallway!
Scientific Notation
• Scientific notation is a method of writing
numbers that can make large or smaller
numbers easier to read.
• Nobody wants to write
24000000000000000000 km over and over
again.
– This is the distance from Earth to the nearest
nieghbour galaxy
Rules for Writing in Scientific Notation
1. Write down all the significant numbers
2. Put a decimal after the first number. (the number
will now be between 1-10)
3. Write “x 10”
4. Write the power corresponding to the number of
places the decimal was (would have) been moved.
(Moving right is negative, moving left is positive)
•
Count the number of digits between where the decimal
was before and where it is now
25 000 000 000 000
4.Write
1.Write
2.Put
a the
down
decimal
power
all after
the
corresponding
significant
the first number.
to the
3.Write
“x
10”
numbers
(the
number
number
of places
will now
the be
decimal
between
was110)
(would
have) been moved. (Moving right
is negative, moving left is positive)
13
25
. x 10
Write 3.42 x 108 in standard notation.
Work in reverse!
As the exponent is positive, we move the
decimal to the right as many times as the
exponent says to.
3.42 x 108 = 342000000
How long would it take…
Formula to find how long it takes to get
somewhere:
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒 =
𝑠𝑝𝑒𝑒𝑑
Ex. How long to travel 550 km going 80 km/h?
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
550 𝑘𝑚
𝑡𝑖𝑚𝑒 =
=
= 6.875 ℎ
𝑠𝑝𝑒𝑒𝑑
80 𝑘𝑚/ℎ
MAKE SURE YOUR UNITS AGREE!
1.3 Where Did The Universe Come
From?
• We don’t really know, but have a theory.
Flavour of the day:
THE BIG
BANG!
What is The Big Bang Theory?
You Tell Me!
The Big Bang
• Observations of galaxies by Hubble and other
astronomers in the 1920s show that the
distant galaxies are all moving away from us at
high speeds proportional to their distances.
• According to the Doppler Effect, this means
that the universe is expanding.
• To be precise, it is space that is expanding, and
carrying the galaxies along as it expands.
• Therefore, the galaxies appear to be moving
away from each other.
• The galaxies themselves are not moving
through space.
• Think of the “balloon analogy”
• If space is expanding, then it is larger now
than it was.
• What would the Universe look like as you go
back in time? What would it look like at half
its age? A quarter?
• If the universe is constantly expanding, this
leads to the conclusion that some time in the
distant past, the universe was so small that it
was just a point.
• This is the beginning of the universe, termed
the “Big Bang”.
• Again, think of it not as an explosion, but a
rapid expansion, such as blowing up a balloon.
Balloon Analogy Activity
• The two dimensional surface of the balloon
will be used as an analogy for the three
dimensional volume of space.
• Draw two dots about a thumb’s width on the
surface of the balloon. Note the seperation.
• Partially blow up the balloon and again note
the seperation of the dots.
• Watch the dots as your partner finishes
blowing up the balloon.
Balloon Analogy Questions
• What happened to the dots as you blew up
the balloon?
– The separation increased
• What was moving: the dots, or the surface of
the balloon?
– The surface of the balloon expanded and carried
the dots with it as it moved through expansion
Balloon Analogy Questions
• What would an ant living on the surface of the
balloon see? Would they see a center or an
edge to their universe?
– They would just see a surface with no center or
edge
• Observations are accumulating to show that
the Big Bang happened about 13 billion year
ago, therefore, this is also the age of the
universe as we know it.
• The Big Bang theory is the best theory of the
origin of the universe we have at this time
because several observations support it.
• First, if this theory were true, we would expect
that in the distant past the universe, being
small and dense, would be very hot. As the
universe (i.e., space itself) expands, it will
cool. The signature of this cooling has been
observed in detail by the COBE satellite in the
early 1990s.
• Second, astronomers know that the element
Helium makes up about one quarter of the
matter in the universe. Indeed, the Big Bang
theory predicts that Helium is produced
during the Big Bang, by exactly the right
amount.
1.4 Evolution of the Universe
Classification of Galaxies
• Examine the following image.
• How would you classify the galaxies pictures?
Hubble Classification of Galaxies
• The best known and often used Hubble
Classification was devised by Edwin Hubble.
• It splits galaxies into ellipticals, spirals, and
irregulars.
Elliptical Galaxies
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has a smooth, featureless appearance
Ellipsoidal (not quite circular) shape
Among the largest of galaxies
Thought to have formed from collisions and
mergers between spiral galaxies
Elliptical Galaxy M87
Dwarf Elliptical Galaxy M110
Spiral Galaxies
• Flattened disc with a bulge and luminous
spiral arms
• Diameter is 10,000 to 300,000 light years
• Only exist if the galaxy is above a certain size
• Our Milky Way Galaxy is a large spiral galaxy
Spiral galaxy NGC 1232
Spiral Galaxy M81
Irregular Galaxies
• Poorly defined structure that doesn’t fall into
the other categories
• Only about 3% of observed galaxies fall into
this category
• May have once been regular galaxies but were
deformed by gravitational pull
• In the early universe, there were many more
irregular galaxies
– This suggests that galaxies used to collide far more
often
Irregular galaxy NGC 1427A
Magellanic Clouds ― Irregular Dwarf
Galaxies
Hubble Deep Field Assignment
• Nelson Case Study 15.6
– Complete letters a – h
– Complete Understanding Concepts #s 1-3
Part Two
The Solar System
2.1 Characteristics of the Solar System
Assignment!
Characteristics to Know
• The sun comprises 99.8% of the total mass of
the solar system.
• All other components, including the planets
and their moons, asteroids, and comets
makeup only 0.2% of the mass.
• In ascending order of the average distance
from the sun, the planets are Mercury, Venus,
Earth, Mars, Jupiter, Saturn, Uranus, and
Neptune
(Distances not to scale)
• Planets, with their moons in tow, revolve
around the sun in nearly circular orbits.
• The largest deviations from circular orbits are
the orbits of Mercury and Pluto.
• Planets orbit the sun on nearly the same
plane. That is, if one were to look at the solar
system on the side, it will look like a very flat
disk.
• Planets revolve around the Sun in the same
direction (counter-clockwise when viewed
from the top, or north, of the solar system).
• The planets may be classified into two groups
with very different properties.
• The inner planets, up to and including Mars,
are called Terrestrial Planets.
• The outer planets, from Jupiter to Neptune,
are called Gas Giants.
• The terrestrial planets are mainly made of
rock and metal; the gas giants are mainly
made of gases.
Relative Sizes of Terrestrial Planets and
Select Moons
• An asteroid belt resides roughly between Mars
and Jupiter.
• Asteroids are large chunks of irregularly
shaped rock, left over from the formation of
the solar system.
2.2 Formation of The Solar System
• The study of the formation of the solar system
is an interesting example of how science
progresses, because it is in its early
development, and many details are still not
understood.
• The chosen theory must explain the previously
discussed characteristics of the solar system.
Current Accepted Theory
• The Evolution Theory aka the Nebula Solar
Theory
• Suggests that the solar system formed from
the contraction of an interstellar dust cloud.
• As the gases in the disk cool, they begin to
condense into solids (ices and dust grains).
• The dust grains collide with and stick to each
other and form progressively larger chunks.
• Over a few hundred thousand years, a few of
these larger chunks grew still larger into the
planets. Around them, similar process formed
their moons.
• Closer to the sun, temperature is very high,
therefore the ices evaporated, leaving the
inner planets the rocky worlds that they are
today.
• Further out from the sun, temperature is
cooler, the gravity of the planets there are
able to incorporate ices to become the
planets’ atmosphere.
• These are the gaseous planets.
Asteroids
• How do you explain asteroids?
– Rocky remnants of solar system formation
• Another theory of the formation of the solar
system, now discredited, is called the
Catastrophe Theory.
• It proposed that the solar system was formed
in an unusual event such as the collision of the
Sun with another star.
• Problem with this theory is that it predicts
that solar systems are too rare
– Scientists have discovered over 100 solar systems
thus far
Blue Spots: Results of Collisions
Between Stars