Chapts 9-10 Flashcards
3 things a navigator needs to know:
- Ship’s position (where they are)
- The course (where they needed to go)
- Ship’s speed
In 600 B.C., a Greek man named _____ discovered
an iron ore that would attract pieces of iron to it.
Thales
What was the name of the iron ore?
Magnetite
When Thales suspended a small piece of magnetite on a string, it always pointed in which direction?
north-south
Because of that, natural magnets became known
as “_____” which means “leading stone”
“lodestone”
English physician who wrote a book on magnetism. He explained that unlike magnetic poles attracted and like poles repelled each other.
William Gilbert
Gilbert believed one pole was somewhere in the _____ and the other was in the _______.
Arctic, Antarctic.
He learned that a compass points north because it aligns with the _______ ______ of the Earth.
magnetic field
Where does the Earth’s magnetic field come from?
The liquid iron layer (and possibly other metals such as
nickel) that surrounds the solid inner core – which generates electric currents that create magnetic fields.
Which planets have magnetic fields?
Jupiter, Saturn, Uranus, and Neptune all have strong fields, Mercury has a weak field.
Who made a “dip
compass”?
William Gilbert
What did Gilbert find out about why a compass points north?
because it aligns with the magnetic field of
the Earth.
When you are at the geographic north pole, the North Star/Polaris is directly overhead. That is considered ____ _____.
True north
The______ ________ _____ is located in the Hudson Bay region of Canada, around 1100 miles away from the geographic north pole.
Magnetic north pole
The southern magnetic pole is between ________ and _________, 1200 miles from the geographic south pole.
Antarctica and Australia
A compass points to the magnetic north pole and therefore, does not always point
____ ____.
true north.
The Earth’s magnetic field is vast, but weak. Because it is weak, it can be upset. One way is by storms on the Sun. Those storms are violent – they send off charged particles that eventually make their way to Earth. We call this a ____ ____ because it messes everything up.
magnetic storm
Distance in degrees north or south of the equator
Latitude
Distance in degrees east or west of the prime meridian
Longitude
What are the circles of latitude called?
Parallels
What are the circles
of longitude called?
Meridians
What is the Latitude
reference line?
The Equator
What is the Longitude
reference line?
Prime Meridian
Powerful country that had a lot of navigation and
shipping resources. It had a large navy with the best
ships. Their ships made it possible to grow their empire.
Great Britain
They picked _____ _________ as the location of 0
degrees longitude.
Greenwich, England
There was also another ancient clock called the water clock, the _______, which means “water thief”
clepsydra
Navigators could use sand glasses to help them
measure the ____ of their ___
Speed of their ship
The difference in degree between true & magnetic north?
11 degrees
The magnetic north pole is located in the
_____ ______ region of Canada, around
1100 miles away from the geographic
north pole
Hudson Bay
The southern magnetic pole is between _______ & ______
, 1200 miles from
the geographic south pole.
Antarctica and Australia
Today ships use a type
of compass called a
_______ compass.
gyroscopic compass
A gyroscopic compass points true north because it is based off of _______’s _______.
Earth’s rotation
The oldest method of measuring time was the …..
sundial
was the scientist and genius that first
understood the principle of the pendulum.
Galileo
developed an
actual clock with a pendulum.
Christiaan Huygens
would eventually make a clock small enough for a
ship. It was a chronometer.
John Harrison
Harrison’s clock went aboard what ship with which captain?
It was taken aboard another ship
called the HMS Bounty with Captain William Bligh.
