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What is a sidereal month and why is it dfferent than a synodic month?
Wiki User
∙ 9y ago
Wiki User
∙ 13y agoSynodic comes from the Latin word synod meaning "meeting" so the moon has to "meet" with the sun every new moon. A synodic month takes 29 1/2 days
A Sidereal month takes only about 27 & 1/3 days, THE MOON MUST COMPLETE MORE THAN ONE FULL ORBIT OF EARTH FROM ONE NEW MOON TO THE NEXT.
that's why a sidereal & synodic month are not the same length
Wiki User
∙ 11y agoThe moon orbits eastward from the earth in 27.32 days. this is called the sidereal period because it refers to a fixed stars. Although the moon orbits earth in 27.32 days, it takes slightly longer to go through its phases. While the moon moves around the sky in 27.32 days, the sun moves eastward about 1 degree per day. In 27.32 days, the moon returns to the same place in the sky where it was last seen, but the sun has moved about 27 degree east, so the moon needs slightly more than 2 days to catch up with the sun and reach new moon again. Thus, one cycle of lunar phases takes 29.53 days an interval called the lunar synodic (rather than "synoptic") period.
Wiki User
∙ 11y agoIt has to do with the facts that 1) a synodic month is calculated based on the moon's position from our point of view relative to the sun, and 2) both the orbit of the moon around the earth and the orbit of the earth around the sun are anticlockwise, and 3) the sidereal month views the position of the moon and earth relative to the fixed stars, ignoring the moon's position relative to the sun.
The above may be difficult to visualize, but with a little thought it becomes clear. Imagine sticking a strip of cardboard to the wall with a tack, or actually do it if the owner of the wall is ok with it. Turn the strip toward the right when it is pointing down and keep going, then to the left when it is pointing up; that is anticlockwise. Imagine that the earth located where the strip is tacked to the wall, and the moon is tacked to the end of the strip. Both the earth and the moon are free to spin on the strip in the anticlockwise direction.
If you imagine the strip pointing straight out to the right, the 3 o'clock position, that is our starting point. Now turn the strip anticlockwise exactly one complete turn, and that is a sidereal month. For sidereal months you ignore what is happening relative to the sun, and that is what you are doing. You can keep turning the strip exactly one whole turn anticlockwise, over and over again, and you will continue to trace out sidereal months.
But position relative to the sun is how you trace out synodic months, and these are the months that are in sync with the moon phases that we observe. That makes perfect sense, because the phases of the moon are determined by how much of the moon's surface is illuminated by the sun.
So turning the strip exactly one time anticlockwise doesn't show what is happening for observers on earth. During the period of time that the moon orbits anticlockwise, the earth is also moving anticlockwise around the sun. To go precisely from one full moon to the next full moon, you have to spin the strip one full turn anticlockwise and then a little extra, to account for this movement of the earth. Hence, we have synodic months that are a little longer than sidereal months.
Wiki User
∙ 9y agoThat is true for most planets, but it actually depends on the direction of the planet's rotation. In fact, on Venus the sidereal day is longer than the solar day.
That's because of the "retrograde" rotation of Venus.
The "sidereal day" is the rotation period of a planet relative to the stars.
That's the "real "rotation period.
The "solar day" is the rotation period relative to the Sun's position in the sky.
Take the Earth as an example. Earth orbits the Sun as it rotates on its axis.
The Earth needs to rotate a little more than one sidereal day to compensate for the change in the Sun's position in our sky that is caused by the Earth's orbital movement around the Sun.
The Earth requires about 4 minutes of extra rotation to put the Sun back in the
"correct" place in the sky. Earth's solar day of 24 hours is about 4 minutes longer than its rotation period (the sidereal day).
Wiki User
∙ 9y agoThe "month" in this case refers to how long it takes for the Moon to go once around Earth. Depending on the reference point chosen, different lengths of months are possible. Sidereal means that the background stars are used as a reference point; synodic means that the Sun is chosen as a reference point (for example, from one new moon to the next). Since Earth moves around the Sun, the Sun's angle among the star changes, so the two reference points are not equivalent.
Wiki User
∙ 13y agoA sidereal month is the time it takes the moon to complete one orbit of earth. A synodic month is longer than a sidereal month because it takes longer for the moon to go through it's phases
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Why is the lunar month longer than the number of days it takes to orbit the earth?
Because the Moon orbits the Earth whereas the Sun and stars do not. So the Moon has real motion apart from what the rotation of the Earth appears to give it. Thus the Moon rises in the East about 20 minutes sooner every day.
What is a complete turn around the earths axis called?
A complete rotation which takes up 1 day or 24 hours.
A lunar month is the period of time from one to the next?
A lunar month is around 29.53 days. It's the length of time between two identical phases, though the actual phase it is measured from has varied from culture to culture. A lunar month could be said to be between full moon to the next full moon for example, but any phase could be used in theory.
How many months does it take the moon to revolve around earth?
It takes the Moon one (1) Month (Moonth) to revolve around the Earth. This is a period of approximately 28 days. In that period we will see a New Moon, First Quarter, Full Moon, Last Quarter and the next New Moon. In the course of 1 year (365 days/12 month), the Moon will revolve around the Earth approximately 12 to 13 times.
What term do astronomers use for the time it takes for a planet to orbit the sun relative to the stars?
Astronomers use the term "sidereal period" to describe the time it takes for a planet to orbit the sun relative to the stars. Sidereal periods are measured based on the apparent motion of a planet against the background of fixed stars rather than against the sun. This allows for more precise measurements of a planet's orbital period.
How many more sidereal months than synodic months are there a year?
1 more sidereal month than synodic month
What is the difference between a sidereal month and and a synodic month?
A sidereal month is the time it takes the moon to complete one orbit of earth. A synodic month is longer than a sidereal month because it takes longer for the moon to go through it's phases
What's the difference between a sidereal year and a synodic year?
A sidereal year is measured based on the planet's position in space relative to the background stars. A synodic year is measured based on the planet's position relative to the star it rotates around (i.e. the sun) Here's an image that is pretty helpful in visualizing.
Why does it take longer for the Moon to go through all of its phases than to come back around to its original point in the sky?
This has to do with the distance that the earth has moved around the sun in that time. The earths progression in that time means that the moon has to travel a little further to get back to the same position relative to earth and the sun (synodic period). This synodic period is longer than the sidereal period, which is the true orbit time of the moon relative to the stars.
How long is a month?
30 days in September, April, June and November - all the rest have 31, except for February, which has 28 (except in a Leap Year, when it has 29). Months are linked to the Moon, but there are different ways of measuring a month. The sidereal month is defined as the Moon's orbital period in a non-rotating frame of reference which is about 27 days, 7 hours, 43 minutes, 11.6 seconds. A synodic month is the most familiar lunar cycle, defined as the time interval between two consecutive occurrences of a particular phase such as new moon or full moon. It is about 29 days, 12 hours, 44 minutes, 2.8 seconds. The tropical month is the average time for the Moon to pass twice through the same equinox point of the sky. It is 27.32158 days, very slightly shorter than the sidereal month (27.32166) days, because of precession of the equinoxes. Unlike the sidereal month, it can be measured precisely. An anomalistic month is the average time the Moon takes to go from perigee to perigee - the point in the Moon's orbit when it is closest to Earth. An anomalistic month is about 27.55455 days on average. The draconic month or nodal month is the period in which the Moon returns to the same node of its orbit; the nodes are the two points where the Moon's orbit crosses the plane of the Earth's orbit. Its duration is about 27.21222 days on average.
Why is the lunar month longer than the number of days it takes to orbit the earth?
Because the Moon orbits the Earth whereas the Sun and stars do not. So the Moon has real motion apart from what the rotation of the Earth appears to give it. Thus the Moon rises in the East about 20 minutes sooner every day.
How long is a it for the moon to revolve around the earth?
It takes roughly one month for the moon to orbit (loosely, to revolve around) the earth - the moon's angle to the sun causing the moon's apparent phases as it does so. Examined in greater detail, here are various distinctions in exactly how the orbit can be interpreted: 1) The sidereal month - the time it takes to orbit the earth with respect to fixed distant stars = about 27.3 days 2) The synodic month - with respect to the sun, when it reaches the same apparent phase = about 29.5 days. (Longer than the sidereal month because the earth has advanced in its orbit around the sun during the month) 3) tropical month - with respect to where the sun is at the vernal equinox = about 27.3 days (barely less than sidereal month) 4) anomalistic month, the interval between perigees or closest point of approach to the earth = about 27.55 days. Note that the same side of the moon faces the earth because its rotational period (spin on its axis) is equal to its orbital period, i.e., tidally locked; but because it is sometimes closer and sometimes further from the earth where the spin and orbit don't "match" there appears to be a slight apparent wobble or libration which allows us to see slightly around the moon's edges. 5) draconic or nodical month - with respect to the ascending node (crossing the orbital plane) = about 27.21 days.
How long is month's?
30 days in September, April, June and November - all the rest have 31, except for February, which has 28 (except in a Leap Year, when it has 29). Months are linked to the Moon, but there are different ways of measuring a month. The sidereal month is defined as the Moon's orbital period in a non-rotating frame of reference which is about 27 days, 7 hours, 43 minutes, 11.6 seconds. A synodic month is the most familiar lunar cycle, defined as the time interval between two consecutive occurrences of a particular phase such as new moon or full moon. It is about 29 days, 12 hours, 44 minutes, 2.8 seconds. The tropical month is the average time for the Moon to pass twice through the same equinox point of the sky. It is 27.32158 days, very slightly shorter than the sidereal month (27.32166) days, because of precession of the equinoxes. Unlike the sidereal month, it can be measured precisely. An anomalistic month is the average time the Moon takes to go from perigee to perigee - the point in the Moon's orbit when it is closest to Earth. An anomalistic month is about 27.55455 days on average. The draconic month or nodal month is the period in which the Moon returns to the same node of its orbit; the nodes are the two points where the Moon's orbit crosses the plane of the Earth's orbit. Its duration is about 27.21222 days on average.
About how long does it take the moon to rotate on its axis?
The moon takes 29.5 days to complete one synodic cycle. This cycle is what we observe from earth, and it is the cycle we would measure from, say, one full moon to the next. However, by the time a synodic cycle ends, the moon has rotated a little more than 360 degrees. This is hard to grasp and takes some time and thought. The rotation of bodies that are orbiting other bodies always presents a need to distinguish between synodic and sidereal rotation. The true, 360 degree sidereal rotation of the moon takes 27.32 earth days. See links on the moon, and on synodic and sidereal periods. Note: Many erroneously conclude that since the same face of the moon always orients toward earth this means that the moon cannot be rotating. However, if you imagine observing from the north the orbiting of the moon around the earth (the moon does orbit the earth-- another idea that some people don't believe), the only way that the same face orients toward earth is for the moon's orbital and rotational periods to be the same. The moon is tidally locked with earth, and this is what causes the orbital and rotational periods to be the same. The face of the moon does in fact change a little due to the phenomenon called libration, a topic beyond the scope of the question. == ==Jeremiah Deem Tulsa - 27.322 days
How long is the moons period of orbit?
There are a lot of ways of looking at this depending on your relation to the Earth/moon system:The Moon's orbital period in a non-rotating frame of reference is 27.32 days (27 days, 7 hours, 43 minutes, 11.6 seconds). This is the sidereal month. It is measured by observing how long it takes the Moon to pass a fixed star.A synodic month is 29.53 days (29 days, 12 hours, 44 minutes, 2.8 seconds) It is measured from New Moon to New Moon. This is the most common way of expressing the lunar cycle.An anomalistic month is the Moon's orbital period measured from perigee to perigee - the point in the Moon's orbit when it is closest to Earth. An anomalistic month is about 27.55 dayson average.The tropical month is the time for the Moon to return to the same ecliptic longitude, i.e. measured from the equinox; it is slightly shorter than the sidereal month because of precession of the equinoxes.The draconic month or nodal month is the period in which the Moon returns to the same node of its orbit (one of the two points where the Moon's orbit crosses the plane of the Earth's orbit). Its duration is about 27.21 days on average.
How much larger in earth days is a year on mars than on earth?
321.7 sidereal days.
How long does is takes the moon to complete all it phases?
For the moon to get back to exactly the right phase, it takes a little longer than its sidereal orbit period, it takes 29 days, 12 hours and 44 minutes in total from full moon to the next full moon. This is known as the synodic period. It takes a little longer to go from phase to phase due to the earths progression around the sun in that time.
