Topic 4- Time And Earth Moon Sun Cycles

Question 1

What is the equation for equation of time

Answer 1

EOT = AST - MST

Question 2

How many minutes does 1 degree equal

Answer 2

4 minutes

Question 3

What is AST

Answer 3

is apparent solar time it is the time the sun shows in the day we can use a sundial for this

Question 4

What is MST

Answer 4

Is mean solar time it is the our watches that humans have invented as the sun is an unreliable way to tell time in society

Question 5

How many minutes can AST be inaccurate

Answer 5

16 minutes

Question 6

What cause AST to be inaccurate

Answer 6

Caused by earth elliptical orbit and axis of earth

Question 7

How many times a year is a sundial accurate

Answer 7

4 times

Question 8

How do you determine the angle of a gnomon on a sundial

Answer 8

The latitude of place

Question 9

Where does gnomon on sundial point to

Answer 9

NCP

Question 10

What are the disadvantage of sundial

Answer 10

Useless when no sun
Inaccurate due to the EOT

Question 11

What day does the summer solstice happen on

Answer 11

21st of june

Question 12

Where does the sun set and rise on the summer solstice

Answer 12

Sun sets in north west and sun rises in north east

Question 13

When is the winter solstice

Answer 13

21st December

Question 14

Where does the sun rise and set on the winter solstice

Answer 14

Sun rises in the south east and sets in the south west

Question 15

When do the equinoxes happen

Answer 15

21st of March and September

Question 16

Where does the sun rise and set on the equinoxes

Answer 16

Rises in east set in west

Question 17

What is a solar/synodic day

Answer 17

Is the time it takes the sun to arrive in the same position as the day before

Question 18

What is a sidereal day

Answer 18

When we measure the rotation not by the sun but by the stars

Question 19

How long is a solar/synodic day

Answer 19

24 hours

Question 20

How long is a sidereal day

Answer 20

23 hours 56 minutes

Question 21

What method do you use to find your local noon

Answer 21

Shadow stick

Question 22

If you moon one degree either way of your location the sun will still culminate at midday but your middy will be when

Answer 22

Will be four minutes earlier or late than previous location

Question 23

What made people convert to MST and why

Answer 23

Trains when they were invented people would fin themselves losing or gaining time when they had reached their destination

Question 24

When more countries started converting to MST what did they decide

Answer 24

They needed a longitude starting point

Question 25

How many meridians did the earth get split into and how many degrees apart

Answer 25

24 meridians and 15 degrees apart

Question 26

Who recognised the problem with with using pendulum clocks on ships

Answer 26

John Harrison

Question 27

What did the horological method help with

Answer 27

Navigators could now tell the local time at Greenwich and easily calculate the difference between there local time and they no longer needed to do complex observations or rely on good weather

Question 28

What was used prior to the introduction of the chronometer

Answer 28

Lunar distance

Question 29

What does lunar distance involve

Answer 29

Calculating the distance between the moon and a prominent star to find navigators longitude

Question 30

How many degrees does the moon move across the sky in 24 hours

Answer 30

13 degrees

Question 31

How did they use lunar distance to calculate longitude

Answer 31

A navigator would measure the the altitude of a prominent star above the horizon
Then they would observe the angle between the moon and star
They then would consult an almanac containing tables of data based on Greenwich
Work out their longitude by using the difference

Question 32

What are the flaws of the lunar distance method

Answer 32

You need a clear sky
Accurate measure to other wise it could result in the navigator being several nautical miles away from destination
Earth is not completely spherical