Transcript Light Year

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Mph
Knots
Mach
Light Year
Warp
• What do theses terms measure?
• Turn to your should partner and discuss for 1 minute. BE
PEPARED TO SHARE
• Mph:
• miles traveled per hour
• Knots:
• time it takes to travel one nautical mile per hour (A nautical mile is longer
than a land mile.)
• Mach:
• an object's speed divided by the speed of sound
• Light Year:
• distance traveled by light in one year
• Warp:
• doesn’t exist, except on Star Trek-speed faster than the speed of light
• Mph: miles traveled per hour
• Knots: time it takes to travel one nautical mile per hour (A nautical mile is
longer than a land mile.)
• Mach: an object's speed divided by the speed of sound
• Light Year: distance traveled by light in one year
• Warp: doesn’t exist, except on Star Trek-speed faster than the speed of light
• How are these terms similar?
• Measurement is a commonality.
• In this unit, one way we measure great distances will be
explored…light years.
Open Measuring
Ruler
(cm)
Entrance Door to
pencil sharpener
Main water shut
off to Xaiver’s
cage
Trash can to
filling cabinet
Lab Table 2 to
Lab Table 7
Length of any
desk in the room
Eye Wash to
Goggle Cabinet
Meter Stick
(m)
Pencil
(pencils)
Yarn
(yarn)
• Which units are best to describe the distances of objects to
the door to the pencil sharpener?
• Which unit was not appropriate for describing the farthest
distance? Why?
• Pencil, difficult to use
• What measurement unit would be used to measure from the
door to your home?
• Kilometers
• What measurement could be used to measure from the door
to the next city? To the Moon?
• Hundreds or thousands of kilometers
• What if we have to measure vast distances from Earth to
another galaxy? Could we use centimeters, meters,
kilometers, miles, and feet?
• Yes, we could use those units, but it wouldn’t be reasonable. The numbers
would be extremely large.
• What type of measuring unit would we need for distances
across space?
• Open Light Year Notes
• Copy what is in yellow
• What type of measuring unit would we need for distances
across space?
• Light Year
• How far is far?
• How fast is fast?
A light year is the
DISTANCE that
light
will travel,
through a
vacuum, in one
year.
Side Note:
This is not a unit of
time, but a unit of
distance.
A vacuum is simply
empty space
• How many seconds are in a year?
• 31,557,600 s/yr
=
The
Speed
of Light
• c = 299,792,458 meters per
second
or
186,000 miles per second
• To get an idea of how fast this
is. . . light can travel about
seven times around Earth in
one second!
• One light year is approximately 5.880
trillion miles or 9.5 trillion km.
• The symbol for light year is “ly”.
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Light years are used to
measure the vast distances
in space.
•In the universe, the kilometer measure is too
small to use.
In the universe, the kilometer measure is too small to use. For
example, the distance to the next nearest big galaxy, the
Andromeda Galaxy, is 21 quintillion km. That's
21,000,000,000,000,000,000 km. This is a number so large that it
becomes hard to write, to relate to, and to use in calculations.
Astronomers use other units of distance.
• Every time you look at
objects in the night sky or
the Sun, the light from
that object is old. You are
looking at history.
•
It takes eight light minutes for light
leaving the Sun to reach the Earth.
•
To put this in perspective, if you could
drive from the surface of the Sun to the
surface of the Earth, it would take you
180 years driving nonstop at 60 mph.
• Sirius, in the constellation Canis
Major, is the sky’s brightest star. It is
easy to find on winter and spring evenings.
• When you look at Sirius, you are
looking back in time to see how
Sirius looked eight years ago. The
light left the star eight years ago.
At some point, we may see the death or birth
of a star long after the event occurred.
• http://janus.astro.umd.edu/astro/distance/
• Why is a light year a unit of distance rather than time?
• It measures the distance light travels in a vacuum in one year - 9.5 trillion km or
5.880 trillion miles.
• Why do we need to use light years as a way of measuring cosmic
distances?
• If we used conventional measurements, the numbers would be huge and difficult
to calculate.
• What is the “speed of light”?
• The rate at which light travels through empty space - 299,792,458
meters/second or 186,000 miles/second.
• How are light years used to measure distances in the universe?
• If we know how fast light can travel from a particular distance, (the Sun), we
can apply this to other objects in our universe.
• http://www.youtube.com/watch?v=ewGsiUPeBD4
• http://www.youtube.com/watch?v=yaX4iGw-b_Y
• Light Year Model
• What is a theory?
• Theories are the most accepted explanation,
based on information from research.
• What is the theory of the Big Bang?
• This theory is based on the observation that
other galaxies are moving away from our
Milky Way galaxy at great speeds in all
directions.
• http://www.youtube.com/watch?v=tFC403WByiA
• Why do some scientists believe that the universe is
expanding?
• It is based on the idea that galaxies are moving away from us.
• Why do scientists revise theories?
• Theories can change if the evidence supports the change.
• Big Bang Research Organizer
• Theories are the most accepted explanation, based on information
from research. Theories can change if the evidence supports the
change.
• While the Big Bang theory is the most popular and widely accepted
theory about the beginnings of the universe and supported by all
the observational evidence, there are other theories that explain the
evidence equally well. But, until further evidence supports a change,
this theory is the currently accepted one.
• You will be researching one of 10 other theories. This handout
models the information you will need to gather. You may summarize
the information about the description of the theory and the evidence,
but try to find all the types of information listed on the sample.
• Please do NOT plagiarize. Paraphrase information in your own
words.
• What is a theory?
• Theories are the most accepted explanation,
based on information from research.
• Why do scientists revise theories?
• Theories can change if the evidence supports
the change.
• NO WARM UP
• You have until 2:00 to complete your research and then we will
share
• What is the theory of the Big Bang?
• This theory is based on the observation that
other galaxies are moving away from our
Milky Way galaxy at great speeds in all
directions.
• Study for your test for the next 5 minutes
• Write “Test” on your Warm Up log
• After the Test:
• Finish your time line
• Work QUIETLY