Why does Earth rotate and what s the evidence? (besides watching it from space ships or satellites) Week 18 January 5, 2015
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 18 TIME 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.
REVOLUTION means to orbit another celestial body 23.5 o tilt ROTATION means to spin on axis
23.5 o tilt WHY DOES THE EARTH ROTATE? http://www.youtube.com/watch?v=fd3p_l2szfi&list=pl316ae0d3f2e1604c
It s called a Foucault pendulum and 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
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
EVIDENCE FOR ROTATION http://www.youtube.com/watch?v=fd3p_l2szfi&list=pl316ae0d3f2e1604c 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?
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
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? 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!
Sun s illumination of Earth as it rotates http://www.learner.org/jnorth/tm/mclass/sunrisesetans.html
REVIEW HOW DOES ROTATION DEFINE THE LENGTH OF A FULL SOLAR DAY (Remember, THIS IS NOT JUST DAYTIME)
WHAT IS ROTATION? How fast does Earth rotate (spin) on its axis at the equator? 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
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? MODEL REAL GLOBE SCALE CITY S LATITUDE MODEL CIRCUMFERENCE LINK - http://www.universetoday.com/26623/how-fast-does-the-earth-rotate/
REVIEW Do 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!
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?
top.scf This finally brings us to time zones. How does rotation relate to your clock?
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 360 o /24 hrs or 15 o /hour Will latitude or longitude help us?
Go 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?
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. C before 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 15 o per zone
NOTEBOOK KEY IDEAS EVIDENCE for ROTATION magnetic field (moving molten material at core) counterclockwise rotation (northern hemisphere) clockwise rotation (southern hemisphere) solar path (east to west) day and night rate of rotation star trails around Polaris Foucault pendulum Time zones
LAB CONCLUSION - STRETCH Lucky you!! For your 16 th 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 (41 o N,74 o W) to reach Brisbane, Australia (30 o S,153 o E) 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.