Time Flashcards
what dimension is time?
4th
what units are covered by time?
- aeon
- millennium
- century
- year
- month
- week
- day
- hour
- minute
- second
what is a year?
time taken for one revolution of Earth on its orbit with reference to a datum direction
what is a Tropical year?
- time taken for one orbit referred to the 1st point of Aries
- 365.242 mean solar days
what is a Civil Year?
- a whole number of days
- hence requires periodic adjustment
which type of calender is in general use?
Gregorian
why is the Gregorian calender used?
maintain alignment with the Tropical Year
how many days has a common year got?
365
how many days has a Leap year got?
366
when are century years not common?
not common unless divisible by 400
millennium years are leap year unless what?
unless divisible by 4000
what are days of the year tabulated against in the Nautical Almanac?
days of the month and week
what is a Day?
time taken for 1 rotation of the Earth on its axis with reference to a datum direction
what shape is the Earth’s Orbit around the Sun?
Elliptical
Which law causes Earth to move at varying rates on its orbit?
Kepler’s Law
