Download Unit 3 - Section 9.7 2011 Universe Origin

Grade 9 Academic Science – Unit 3 Space
Origin and Evolution of the Universe
Section 9.7 Pages 393-397
On 4 June 2002, a new planet-like object was observed circling the Sun more than one and a half billion
kilometres beyond Pluto. Named Quaoar, it is nearly 1,280 kilometres wide (…half the size of Pluto, larger
than Pluto’s moon Charon OR about one-tenth the diameter of Earth) and circles the Sun every 288
years. Quaoar is the biggest astronomical find in the Solar System since the discovery of Pluto 81 years
ago.
How was Quaoar detected?
It was observed with the aid of the Hubble Telescope.
So…
The Hubble Telescope was named for American astronomer Edwin
Hubble. He (1) identified individual stars outside the Milky Way
galaxy and (2) determined the Universe was expanding outward.
 Prior to Hubble, it was believed the only stars in the
Universe occurred in the Milky Way, while the rest of the
Universe was mainly gas and dust. Hubble observed stars
in the Andromeda galaxy.
 Hubble realized the galaxies were moving apart. Hubble
measured RED SHIFTS in the light emissions from the galaxies and observed that the galaxies
were moving away from each other at a rate constant to the distance between them. In 1929, he
produced Hubble’s Law: The Universe is expanding at a constant rate as determined by the
linear proportional relationship between recessional velocity (i.e., rate at which an object is
moving away from Earth) and distance. Hubble’s Law suggests the greater the distance from
Earth, the faster the movement is occurring. This finding has helped astronomers determine the
age of the Universe and prove that the Universe was expanding. (NOTE: Albert Einstein had
used his Theory of Relativity in 1917 to predict the Universe was expanding. Einstein suggested
that space was curved by gravity, and therefore, it must be able to expand or contract. He found
his idea so far fetched that he rejected the idea.)
Red Shift
 See Page 394 in your textbook for an illustration
 The Red Shift is a pattern of light. In space, each galaxy emits its own
distinctive spectrum of light. This distinct pattern, the Light Spectra,
shifts depending on
whether the light source
is moving or stationary.
Literally, the wavelength
of light is stretched…
towards the red end of
the spectrum. Thus, a
Red Shift is the
phenomenon of light
from galaxies shifting toward the red end of the
visible spectrum demonstrating that the galaxies
are moving away from Earth.

To understand more, watch the “Ask an Astronomer” You Tube “What is a Redshift?”
presentation at http://www.youtube.com/watch?v=FhfnqboacV0
How would you know a shift has occurred…since light travels very fast and we do not observe any
spectral shift in our daily lives? HINT: Comparison…”to what?”
For fun, watch the “Ask an Astronomer” You Tube clip called “Why aren’t there any Green Stars?” at
http://www.youtube.com/watch?feature=endscreen&v=BvjeP3SfD1g&NR=1
Dark Matter
Space is mostly black and empty. However, something must occupy the mass called space. Dark Matter
is an undetermined type of matter thought to be the undefined mass of the Universe. Dark matter does
not emit or scatter electromagnetic radiation (…including visible light), and as such, dark matter cannot be
seen. Yet, dark matter is estimated to makeup 83% of the matter in the Universe.
Isn’t space fun?
How would I know about dark matter if it is not seen…and presently, largely undefined?
To answer a question, you start with what you know.
 The Universe is expanding
 Expansion can be determined by Red Shifts
 Light moves across space as electromagnetic radiation
 Gravitational Forces exist throughout the Universe, and these forces influence other objects in
space
 Stars are luminous (i.e., emit light)
 Luminosity (i.e., amount of light emitted) is used to determine the size and mass of stars.
 …and more
Scientifically, the size of a galaxy is estimated using, among other measures, luminosity. If I know an
object’s luminosity, I can determine its mass. Yet, non-random discrepancies and errors occurred in the
measurements. That is, the expected luminosity and the observed luminosity were slightly different. It
seemed the observed luminosity was greater or pulled in unanticipated directions….by unseen mass or
gravitational force, respectfully. Moreover, the discrepancies showed a consistent pattern such as
amount and shift. To account for the error, dark matter must exist. Dark matter is something that has a
gravitational force.
More interestingly, the Universe contains lots of dark matter.
 Some dark matter may consist of ordinary matter (e.g., contains atoms) but does not emit
electromagnetic radiation. This is called baryonic dark matter.
 Most dark matter is non-baryonic dark matter. It is not composed of ordinary matter, carry electric
charges or interact with ordinary matter via electromagnetic radiation. It may contain neutrinos
and supersymmetric particles (…ha…prove that on…all theoretical to date…) that undergo total
destruction to produce observable photons. Most often, non-baryonic dark matter can only be
inferred by observed gravitational attraction.
Do you believe it?
The June 1988 Scientific American article “Is dark matter theory or fact?”
(http://www.scientificamerican.com/article.cfm?id=is-dark-matter-theory-or) notes dark matter reveals its
presence via the gravitational effect it exerts on luminous matter (i.e., matter seen with telescopes) in the
Universe.
 The best example of the gravitational effects of dark matter is observed when looking at the
rotation of galaxies. Galactic rotation is observed via the Light Spectra of stars in each part of the
galaxy. When the light from a star is observed using a prism, the starlight is separated into its true
colours with a specific wavelength of light. The wavelengths “show” which elements the stars
contain, and thus, a star's composition. When a star is moving away from us, all of the



wavelengths of the spectral lines are shifted to higher values (i.e., red) than they would have
been were the star stationary or moving side to side (neither towards nor away from us). This
shifting is known as a Doppler shift. By measuring the shift in wavelength, the speed of
movement away (red) or towards (blue) Earth can be calculated.
When a galaxy is rotating, the starlight from stars on the side of the galaxy that is moving towards
are blue-shifted (…think opposite of Red Shift), while the starlight from the stars on the other side
of the galaxy are red-shifted. Thus, the speed and
direction that a star in the galaxy is orbiting about the
centre of the galaxy can be observed.
When stars orbit the centre of a galaxy, their orbital
speed is determined by the distribution of the mass
contained within the galaxy. A graph showing the
orbital speeds of the stars versus their distances
from the centre of the galaxy is the "rotation curve"
for the stars in the galaxy.
By adding all the luminous matter seen in the galaxy
(…including stars, gas and dust…) and using
Newton’s laws of gravitational physics, the speed of
stars should decrease in a predictable manner the
father away they are from the centre of the galaxy.
This was NOT observed. Rather, stars far from the
centre move faster than expected. To account for
this observation, dark matter must exist in the
galaxies…in a large, spherical distribution known as
a galactic halo.
Neat, eh?
Dark Energy
If the Universe is expanding at a steady rate, it is logical to think that at some point the Universe will slow
its expansion, eventually start to contract (i.e., shrink) and, once again, become a singularity. “We are all
doomed,” you yell. Well, not yet. The Universe is expanding. Moreover, the rate of expansion is
increasing. Some unknown and unexplainable force, called DARK ENERGY, is offsetting the force of
gravity and causing the Universe to expand faster.
Essentially, dark energy has the opposite function of dark matter. Dark matter brings things together by
gravitational force; whereas, dark energy is an unseen and unknown agent that drives things apart.
Big Bang Theory
Task
 Write a summary of your perception of the Big Bang.
 Write or draw a short story that incorporates accurate and essential parts of the Big Bang.
 Draw a cartoon depicting accurately the Big Bang.