Week 18 – January 5, 2015

Why does Earth rotate and what’s the evidence?

(besides watching it from space ships or satellites)

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

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.

23.5o tilt

ROTATIONmeans to spin on axis

REVOLUTIONmeans to orbit another celestial body

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

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

How does this photo of an

illuminated Earth & Moon seen from

space by the Galileo probe

relate to rotation?

Remember it isn’t just Earth…Here’s an illuminated Jupiter & one

of its moons seen from space by the Galileo probe

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

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

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?

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

REVIEWHOW DOES ROTATION DEFINE

THE LENGTH OF A FULL SOLAR “DAY”

(Remember, THIS IS NOT JUST DAYTIME)

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?

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/

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

We can also use Polaris to find our latitude in northern hemisphere based on Polaris’ altitude(angle in sky) above the horizon.

What latitudes do these star trails around Polaris show?

Lowest latitude? Highest latitude Mid-latitude?

This finally brings us to time zones.How does rotation relate to your clock?

Show Desktop.scf

http://www.timeanddate.com/worldclock/

Why is

longitude

the basis

for time

zones

around the

world?

Week 18

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

Earth rotates 360o /24 hrsor 15o/hour

Will latitude or longitude

help us?

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/

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.

How times relate to a solar day

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

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

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.