draconic months造句

• However, the synodic and draconic months are incommensurate : their ratio is not an integer number.
• The saros is an eclipse cycle of 223 synodic months = 239 anomalistic months = 242 draconic months.
• After one nodal precession period, the number of draconic months exceeds the number of sidereal months by exactly one.
• This animation shows a set of 50 simulated views of the Moon from the center of the Earth over one draconic month.
• A draconic month is shorter than a sidereal month because the nodes move in the opposite direction as the Moon is orbiting the Earth, one revolution in 18.6 years.
• In the time it takes for the Moon to return to a node ( draconic month ), the apparent position of the Sun has moved about 29 degrees, relative to the nodes.
• A draconic month is shorter than a sidereal month because the nodes move in the opposite direction to that in which the Moon is orbiting the Earth, one revolution in 18.6 years.
• This is the reason that a draconic month or nodal period ( the period of time that the Moon takes to return to the same node in its orbit ) is shorter than the sidereal month.
• Note that the 19-year cycle is also close ( to somewhat more than half a day ) to 255 draconic months, so it is also an eclipse cycle, which lasts only for about 4 or 5 recurrences of eclipses.
• As seen from the Earth, the time it takes for the Moon to return to a node, the draconic month, is less than the time it takes for the Moon to return to the same ecliptic longitude as the Sun : the synodic month.
• Eclipse cycles have a period in which a certain number of synodic months closely equals an integer or half-integer number of draconic months : one such period after an eclipse, a node of the Moon's orbit on the ecliptic, and an eclipse can occur again.
• Since there may be an eclipse every half draconic month, we need to find approximations for the number of half draconic months per synodic month : so the target ratio to approximate is : SM / ( DM / 2 ) = 29.530588853 / ( 27.212220817 / 2 ) = 2.170391682
• Since there may be an eclipse every half draconic month, we need to find approximations for the number of half draconic months per synodic month : so the target ratio to approximate is : SM / ( DM / 2 ) = 29.530588853 / ( 27.212220817 / 2 ) = 2.170391682
• Each saros series starts with a partial eclipse ( Sun first enters the end of the node ), and each successive saros the path of the Moon is shifted either northward ( when near the descending node ) or southward ( when near the ascending node ) due to the fact that the saros is not an exact integer of draconic months ( about one hour short ).
• However we know that if an eclipse occurred at some moment, then there will occur an eclipse again " S " synodic months later, " if " that interval is also " D " draconic months, where " D " is an integer number ( return to same node ), or an integer number + ?( return to opposite node ).
• Note that there are three main moving points : the Sun, the Moon, and the ( ascending ) node; and that there are three main periods, when each of the three possible pairs of moving points meet one another : the synodic month when the Moon returns to the Sun, the draconic month when the Moon returns to the node, and the eclipse year when the Sun returns to the node.
• These three 2-way relations are not independent ( i . e . both the synodic month and eclipse year are dependent on the apparent motion of the Sun, both the draconic month and eclipse year are dependent on the motion of the nodes ), and indeed the eclipse year can be described as the beat period of the synodic and draconic months ( i . e . the period of the difference between the synodic and draconic months ); in formula:
• These three 2-way relations are not independent ( i . e . both the synodic month and eclipse year are dependent on the apparent motion of the Sun, both the draconic month and eclipse year are dependent on the motion of the nodes ), and indeed the eclipse year can be described as the beat period of the synodic and draconic months ( i . e . the period of the difference between the synodic and draconic months ); in formula:
• These three 2-way relations are not independent ( i . e . both the synodic month and eclipse year are dependent on the apparent motion of the Sun, both the draconic month and eclipse year are dependent on the motion of the nodes ), and indeed the eclipse year can be described as the beat period of the synodic and draconic months ( i . e . the period of the difference between the synodic and draconic months ); in formula: