3. Cosmology
• the branch of astronomy that deals with
the origin, large-scale properties, and
the evolution of the observable universe
4. The Universe
• in astronomy, the sum total of all things which
can be directly observed or whose physical
effects on other things can be detected
• in simpler terms, space and all the matter and
energy in it
• major components:
– galaxies
– solar systems
– planets
Can you think of something in
the universe that cannot be
seen, but its effects on other
things can be detected?
5. “Big Bang” Theory
• the primeval explosion of space, time, matter and
energy that most astronomers think gave rise to the
universe as we see it today.
• occurred about 13.7 billion years ago
• thought to have expanded within a second from
something the size of a spec of dust to the size of
our solar system
Misconception Alert:
Describing this theory as
the “Big Bang” is a misnomer
because there really was not
an explosion, just a release of
energy
6. Edwin Hubble
• determined that other
galaxies exist, besides
the Milky Way
• observed that galaxies
were moving away from
each other
– Hubble Law – the farther
away a galaxy is, the
faster it is moving away
from us; supports the Big
Bang Theory Image taken from:
http://apod.nasa.gov/apod/ap960217.html
7. Arno Penzias & Robert Wilson
• accidentally detected faint radiation on
a radio telescope in 1965
• determined that the radiation was
leftover thermal energy from the “big
bang”
Image taken from:
http://www.einstein-online.info/en/elementary/cosmology/early_universe/index.html
8. Galaxy
• a large assemblage of stars (and often gas and dust), typically
containing millions to hundreds of billions of member stars
– Star - a large hot ball of gas which generates energy in its core by nuclear
reactions
• around 100 billion in the universe
• held together by the gravitational attraction of all its member
stars on one another
• formed around 200 million years after the “Big Bang”
• most large ones seem to have super-massive black holes at their
centers
• sometimes contain very bright centers called quasars
• 3 major types:
– Spiral
– Elliptical
– Irregular What is the name
of the galaxy
we reside in?
9. 3 Types of Galaxies
Spiral
have arms of stars, gas ,
and dust that curve away
from the center of the
galaxy in a spiral pattern
Ex. – Milky Way
Elliptical
shaped like
spheres or eggs;
have almost no
dust or gas
between stars;
contain old stars
Irregular
faint galaxies without
a definite shape;
smaller than the other
types of galaxies;
contain fewer stars
The process of galaxies colliding to create a larger galaxy is known
as “galactic cannibalism.”
Images taken from: http://school.discoveryeducation.com/schooladventures/universe/galaxytour/toknow.html
10. Constellation
• a group of stars that form a pattern in the sky
• stars of a constellation are often far apart from each
other, but they appear grouped together when viewed
from Earth
• one of 88 sectors into which astronomers divide the
sphere of the sky – named after a traditional constellation
in that sector
• patterns of constellations are dynamic; therefore, the
constellations of 100,000 years ago are quite different
from today’s
• a part of a constellation that forms its own pattern in the
sky is known as an asterism (ex. – The Big Dipper)
Why is it not possible to see all constellations at once?
11. Wherever you are on Earth, many stars
and constellations always remain hidden
from your view by the planet itself.
Moreover, because of the Earth’s being in
constant motion, your local sky changes
both overnight and season to season.
12. Solar System
• the sun and all things orbiting around it,
including the eight major planets, their
satellites, and all the smaller pieces such as
asteroids and comets
• formed around 4.6 billion years ago
Image taken from:
http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg
13. Planet
• derived from a Greek word
that means “wanderer”
• a major object which orbits
around a star
• in our solar system, there are
eight such objects which are
traditionally called “planets”
14. Asteroids
• small, solid, rocky
bodies that orbit close
to the Sun
• most found between
the orbits of Mars and
Jupiter in the
“Asteroid Belt”
• thought to be leftover
material from the
formation of the solar
system
• range in size from
1000 km or 621 miles
(Ceres) to the size of
pebblesImage taken from:
http://www.windows.ucar.edu/tour/link=/our_solar_system/asteroids.html
15. Meteoroid, Meteor, Meteorite
• Meteoroid – solid debris from space
(asteroids) that are moving
towards Earth
• Meteor
– a brief streak of light produced by
a small particle entering Earth’s
atmosphere at high speed
– often referred to as “shooting
stars” or “falling stars”
– travel at speeds between 11-72
kilometers per second (6.8 – 44.7
miles per second)
• Meteorite – a small object from
outer space that passes through
Earth’s atmosphere and reaches
the surface
• Freehold Meteorite - MSNBC
• Freehold Meteorite - USA-Today
Meteoroid (asteroid)
Meteor
Meteorite
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
What causes a meteor
shower to occur?
16. Meteor showers occur when the earth
in its orbit around the Sun passes
through debris left over from the
disintegration of comets.
17. Comet
• a small body of ice and
dust (“dirty snowball”)
that orbits the Sun
• contain a head (coma)
followed by a tail(s) of
gas and dust
• the tail always points
away from the sun and
can be millions of
kilometers long (but the
amount of matter it
contains can be very
small)
Image taken from:
http://www.space.com/bestimg/index.php?guid=45b0fd31f065d&cat=bestcomet
18. Satellite
• an object that orbits a more massive
object (i.e. – moons)
• probes we launch into orbit around the
Earth are called “artificial satellites”
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
19. Telescope
• a device that gathers electromagnetic radiation
• Types:
– Visible, infrared, ultraviolet – pick up visible,
infrared, and ultraviolet waves
• Reflecting - use mirrors that reflect the image being
viewed
• Refracting – using lenses, gathers light and focuses it
near the opposite end of the tube; works like a magnifying
glass
– Radio - pick up radio waves emitted from space;
not effected by variables like weather or clouds
Internet Telescope
20. Hubble Space Telescope
• a reflecting
telescope that was
placed into orbit in
1990
• sends images and
measurements back
to Earth
electronically
What is one of the main
benefits of having the Hubble Space
Telescope in orbit, as opposed to
it being here on Earth?
Image taken from:
http://hubblesite.org/gallery/
21. Astronomical Unit (AU)
• unit of distance equal to the average spacing
between the Earth and the Sun
• equal to about 150 million kilometers (93
million miles)
• light takes about eight minutes to cover this
distance
150 million km
(93 million mi.)
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
22. Light Year
• the distance that light travels in one year in a
vacuum, which is about 9.5 trillion kilometers
(6 trillion miles)
– The Milky Way Galaxy is about 100,000 light years
in diameter
• the speed at which light travels this distance
is about 300,000 km/sec (186,000 mi/sec)
The second closest star to the Earth is a
little over four light years away. How far
away (in miles) is the star?
24. Parsec
• unit of distance equal to about 3.26
light years (or 206,265 AU)
If one parsec equals 206, 265 AU, how
many miles is it equal to?
The astronomical unit (symbol: au , ua,
or AU) is a unit of length, roughly the
distance from Earth to the Sun and equal
to about 150 million kilometres (93 million
miles).
25. Parallax
• the apparent shift in position of an
object when viewed from different
locations
• used by astronomers to measure
distance
Parallax Simulation
Parallax Simulation – 1
Parallax Simulation - 2
Find the Distance to HT Cas Using Parallax
Put your pointer finger in front of your face and begin
opening and closing your eyes in an alternating manner. What
do you notice about the your finger’s position?
