Topic 4 Flashcards
(15 cards)
name 3 astrological methods for determining longitude
-stellar angle measurements
-lunar distance measurements
-satellite based methods
describe stellar angle measurements
used to measure longitude
involves measuring angle between moon and specific star at certain time
describe lunar distance method
-used to measure longitude
-measures angles between moon and other celestial bodies
-compared with tables in Nautical Almanac to determine local time & longitude
describe satellite based methods
-modern technique to determine longitude
-uses GPS satellites to accurately pinpoint longitude
-tramsit signalds that allow receivers on earth from several satellites
-thus determine their longitude
state 3 horological methods of determining longitude
marine chronometer
portable timekeepers
radio and atomic clocks
describe using a marine chronometer to determine longitude
-this is a clock accurate enough to keep GMT at sea
-u can use by comparing GMT on clock to local time (determine using sun)
which horological method to determine latitude is used in the modern day
radio and atomic clocks
give an example of a portable time keeper
H4 by John Harrison
approximately how wide is each time zone
15 degrees
name 1 adv and 1 disadv of time zones
ADV:
allow for uniform understanding of time across the world simplifyig global communications, transport, scheduling etc
DISADVM
despite standardisation, time zones may sometimes add to the complexity due to use of different standards, local decisions etc
name 3 things ancient civilisations used for lunar phase cycle for
calendar keeping, navigation, agriculture
what 2 factors influence EOT
-earth’s axial tilt
-earth’s elliptical orbit
what is represented on an analemme
changing position of sun throughout the year
whats the table called that u use in lunar distance method
Nautical Almanac
