Why does Earth rotate and what’s the evidence? (besides … rotation and time... · 2015. 1....
Transcript of Why does Earth rotate and what’s the evidence? (besides … rotation and time... · 2015. 1....
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Week 18 – January 5, 2015
Why does Earth rotate and what’s the evidence?
(besides watching it from space ships or satellites)
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The sun determines our solar time everywhere on earth as Earth rotates. Can you can imagine why we use longitude to
establish time zones?
Read pages 30-31, take notes to figure out time zones, using Cornell note format.
You need to understand how it works before creating a time zone wheel in Lab 10
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Week 18TIME ZONES VOCABULARY
latitude
longitude
meridians
Prime Meridian
International Date Line
military time
time zones & longitude
time zones & political boundaries
Greenwich Mean Time (GMT)
ZULU [time]
Universal time
rotation rate (solar day)
Rotation rate (land speed)
rotation direction
solar day times
earlier time in day (west)
later time in day (east)
You should be able to define, provide examples and use these terms. Check them off as we use them.
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23.5o tilt
ROTATIONmeans to spin on axis
REVOLUTIONmeans to orbit another celestial body
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WHY DOES THE EARTH ROTATE?
http://www.youtube.com/watch?v=fD3P_l2sZFI&list=PL316AE0D3F2E1604C
23.5o tilt
http://www.youtube.com/watch?v=fD3P_l2sZFI&list=PL316AE0D3F2E1604C
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It’s called a Foucault pendulumand its evidence for rotation. Here’s how it works.
http://www.youtube.com/watch?v=M8rrWUUlZ_U
Have you ever seen one of these work ?http://www.youtube.com/watch?v=WZ3bi5IVToE
http://www.youtube.com/watch?v=M8rrWUUlZ_Uhttp://www.youtube.com/watch?v=WZ3bi5IVToE
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How does this photo of an
illuminated Earth & Moon seen from
space by the Galileo probe
relate to rotation?
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Remember it isn’t just Earth…Here’s an illuminated Jupiter & one
of its moons seen from space by the Galileo probe
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1. In which direction does the sun generally rise each day?
2. In which direction does it generally set?
3. What does that tell you about the direction of planet rotation?
EVIDENCE FOR ROTATION
http://www.youtube.com/watch?v=fD3P_l2sZFI&list=PL316AE0D3F2E1604C
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What type of motion is this diagram showing?PROVE IT TO YOURSELF with the globes – counterclockwise
in northern hemisphere and clockwise in southern hemisphere but always towards the east
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THE EARTH ROTATES TO THE EAST so the sun appears to move from east to west
across the sky. Try it with a flashlight and globe!
Is this evidence for rotation?
http://www.youtube.com/watch?v=fD3P_l2sZFI&list=PL316AE0D3F2E1604C
Why does the sun generally rise in the east in the morning and
set in the west at night?
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http://www.learner.org/jnorth/tm/mclass/SunriseSetAns.html
Sun’s illumination of Earth as it rotates
http://www.learner.org/jnorth/tm/mclass/SunriseSetAns.html
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REVIEWHOW DOES ROTATION DEFINE
THE LENGTH OF A FULL SOLAR “DAY”
(Remember, THIS IS NOT JUST DAYTIME)
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WHAT IS ROTATION?
RATE can be measured in DEGREES of ARC of a CIRCLE or
using a real world distance like EQUATORIAL CIRCUMFERENCE
(from NASA) of 40,030 km = 24,874 mi
How fast does Earth rotate (spin) on its axis at the equator?
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Does Earth rotate at the same rate everywhere?
Let’s spin to find out how its rotational speed varies
Check this using the equatorial circumference (km) and a circumference measured on the same latitude as one of your cities.
How will you measure your city’s rotation distance? GLOBE
SCALEMODEL
REALCITY’S LATITUDE
MODEL CIRCUMFERENCE
LINK - http://www.universetoday.com/26623/how-fast-does-the-earth-rotate/
http://www.universetoday.com/26623/how-fast-does-the-earth-rotate/http://www.universetoday.com/26623/how-fast-does-the-earth-rotate/
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REVIEWDo you know why
Polaris is called the North Star?
More evidence for rotation!• It’s used to find north in northern hemisphere since
it’s circumpolar (does not appear to move) as Earth rotates. Causes star trails around it!
http://www.youtube.com/watch?v=3V3rmDG5J8A
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We can also use Polaris to find our latitude in northern hemisphere based on Polaris’ altitude(angle in sky) above the horizon.
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What latitudes do these star trails around Polaris show?
Lowest latitude? Highest latitude Mid-latitude?
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This finally brings us to time zones.How does rotation relate to your clock?
Show Desktop.scf
http://www.timeanddate.com/worldclock/
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Why is
longitude
the basis
for time
zones
around the
world?
Week 18
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Lab – Time Zones
How does local time
around the world
compare to ZULU,
GMT, & Universal
Time in Greenwich,
England at the
Prime Meridian?
Week 18
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Earth rotates 360o /24 hrsor 15o/hour
Will latitude or longitude
help us?
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How do the straight zones relate to the real world?
What do these zones represent?
Are these time zones really straight in the real world?
Go
http://www.timeanddate.com/information/http://www.timeanddate.com/information/http://a.tribalfusion.com/j.u?rnd=1895684912&redirect=http://www.aboutads.info/choices/http://a.tribalfusion.com/j.u?rnd=1895684912&redirect=http://www.aboutads.info/choices/
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Now let’s create our own time zone wheel and see what time it
is anywhere you want to go!!!Lab 10 – Time Zones
Once you get the cut-out wheel and background page together,
get them checked by Ms. Cbefore you go on.
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How times relate to a solar day
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I won’t have a “wheel” in the real world…How do I determine time zones without it?
How many time zones or hours away from GMT in standard time (not daylight savings time)?
= CITY LONGITUDE
15o per zone
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NOTEBOOK KEY IDEASEVIDENCE for ROTATION
magnetic field (moving molten material at core)counterclockwise rotation (northern hemisphere)clockwise rotation (southern hemisphere)solar path (east to west)day and nightrate of rotationstar trails around PolarisFoucault pendulumTime zones
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LAB CONCLUSION - STRETCH
Lucky you!! For your 16th birthday your parents have
decided to send you snorkeling at the Great Barrier
Reef in Australia! Hope you can swim!
It takes about 36 hours to get there if you are traveling
east. You can’t miss the plane, so at what time would
you have to leave LaGuardia in, NYC (41oN,74oW) to
reach Brisbane, Australia (30oS,153oE) by 14:00?
For both cities be sure to include evidence with your
calculations: latitude and longitude, military time and
clock time, and how many time zones to Brisbane,
Australia from NYC.