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WHERE ARE WE IN THE
UNIVERSE?
Text 7.1: Space Flight to the Stars p.g. 258-266
Agenda
1.
2.
3.
4.
5.
6.
Minds On: Where Are We in the Universe?
Are We Alone in our Galaxy?
Measuring Distance in Space
Scientific Notation – Task
Properties & Types of Galaxies
Quick Lab – All These Worlds
Learning Goals

By the end of the class, we should be able to
 Describe
how the model of the atom has changed over
time
 Describe the structure of the atom according to modern
atomic theory
 Calculate the number of protons, neutrons and electrons
in an atom based on the periodic table
Minds On: Where Are We in the
Universe?
http://www.youtube.com/watch?v=
17jymDn0W6U&feature=player_e
mbedded
Are We Alone in the Galaxy?
Are We Alone in the Galaxy?
Are We Alone in the Galaxy?

Milky Way Galaxy:
 100

000 Light Years
in diameter
 Estimated 100 – 400
billion stars
Mapping of universe
shows over 107 000
galaxies out to a
distance of 5 billion ly
Measuring Distance in Space

Distances are so VAST we
have had to develop a
special system:
 Astronomical
unit (AU)
 Average distance between the
Sun & the Earth
 1AU = 150 million km (150
000 000km)
Measuring Distance in Space
Measuring Distance in Space


Outside the solar system the distances to other celestial
objects become to great…
For this we use LIGHT YEARS (ly):
 Equals
the distance a beam of light can travel through space
in a year
• Light Year = 63 000 AU
or 9 000 billion km
• At the speed of light
you could travel around
the earth 7 times in 1
second
Scientific Notation


Scientific notation helps make very large numbers
shorter and easier to handle
E.g. The speed of light is about 299 800 000 m/s.
Write this in scientific notation
Step 1: Move decimal place to 1st digit 2.99800000
Step 2: Count number of places. Exponent of 8, written as 108
Step 3: Delete zeros & rewrite 2.998 x108 m/s
Scientific Notation

Scientific Notation – Task:
 Complete
p.g. 265
questions 1-6
What is a Galaxy? Properties?

Galaxies – contain stars, planets,
and dust all bound together
through gravity.
Greek – galaxias literally means
“milky” reference to the milky way
 Black Holes – is a region of space
where gravity is so strong that
nothing, not even light can escape.
 Dark Matter – refers to matter in
the universe that is invisible because
it does not interact with light or any
other kind of radiation.
 Star Clusters – distinct groupings of
stars i.e. open cluster (young) or
globular cluster (old).
Black hole in the milky way galaxy
has a mass equal to 3 million stars!

Most of the gravity in the
universe is thought to be
produced by dark matter.
What is a Galaxy? Properties?

Galaxies
are
classified
into four
main shapes:





Spiral
Barred
Elliptical
Irregular
Classified
using Edwin
Hubble’s
Tuning fork
What is a Galaxy? Properties?



Galaxies tend to
occur in groups
called clusters.
Galaxy clusters in
turn from groups
called super
clusters.
Could be over 100
million galaxies in
the universe.
Quick Lab – All These Worlds

Complete the quick lab C4 –
All These Worlds
 Questions
1-4 p.g. 266
 Are there other forms of life
on the universe? Explain…