Space Flashcards
(55 cards)
What is declination
Angle in degrees n/s or the celestial equator
What is Greenwich hour angle
Defines position of longitude measured from Greenwich celestial meridian
What is a zenith
Position of a body overhead the observer at 90° (altitude 90°)
What is the local hour angle
The angular measurement from an observers celestial meridian to the celestial meridian of the body
What are Kepler’s laws
The orbit of each planet is an eclipse, with the sun at one of the focal points
The line joining the planet to the sun, known as the radius vector, sweeps out equal area in equal time
When is the earth closest to the sun
Perihelion = 3rd January
When is the earth furthest from the sun
Aphelion = 3rd July
When is the summer solstice
21st June
Sun = 23.5°N
When is the autumnal equinox
21st September
Sun = 0°
When is the winter solstice
21st December
Sun = 23.5°S
When is the spring equinox (vernal)
21st March
Sun = 0°
What is the plane of the ecliptic
The plane of the earths orbit round the sun
What is the angle between the celestial equator and the suns orbit (the obliquity of the ecliptic)
23.5°
What / where is the Tropic of Cancer
23°27’N
Declination of sun at summer solstice
What / where is the Tropic of Capricorn
23°27’S
Declination of sun at winter solstice
Where is the artic circle
66°33’N
What happens with daylight at the artic circle
At summer solstice the suns rays will pass over the North Pole and places north of the artic circle will have continuous daylight
Where is Antarctic circle and what happens in summer solstice
66°33’S
At summer solstice the sun does not rise
When is the minimum rate of change of daylight
Solstices at mid latitudes
Where is the maximum rate of change in daylight
Equinox at mid latitudes
What is the sidereal year
The period between 2 successive conjunctions of the earth, sun and a fixed point in space (365 days 6 hours)
What is the tropical year
Period between 2 successive vernal equinoxes I.e. time taken for one orbit round the sun relative to the first point of Aries
365 days 5 hours 48mine 45.98 seconds
When can / can’t you have a leap year
YES If year is divisible by 4 (1952,1976)
NO if the year is also divisible by 100 (1700,1800,1900)
YES If year is also divisible by 400 (1600,2000)
What is a sidereal day
Period between 2 successive transits of s particular meridian and a fixed point in space. Constant time interval of approximately 23 hours 56.3 mins
