Kuuipo, your question is somewhat confusing through incomplete specification; that's why there may also be (matching?) confusion in some other responses. (But then, perhaps that was what you intended?)
1. You need to specify the distance of WHAT? (The object referred to by "its" --- "its" must refer to something already mentioned, but "distance" or "Sun" are the only prior candidates in your sentence; and a language purist would even object to the latter as it's merely part of a preceding [subsidiary] adjectival phrase.)
2. If "it" is the Earth, then fundamentally, trying to "calculate its period of revolution" is logically circular. The reason for this is that the quantity G x M_sun (the combination that appears in the Sun's gravitational attraction) is only known BECAUSE it's what is needed to give the OBSERVED period of Earth's revolution! We have NO independent way of obtaining the Sun's mass, for example; historically, the value of G was measured ingeniously on Earth (Maskerlyne, Cavendish, ...), then fed into the formula for P to give us M_sun from the KNOWN P.
In other words, WE ONLY LEARNED M_sun BECAUSE WE ALREADY KNEW P_Earth and G!
(There's a lot of needless confusion about this. I even have a distinguished colleague who FOR YEARS has asked his undergraduate students to work out the value of G from the length of the year and the mass of the Sun. (!!) I suppose that this sort of logical travesty is inevitable when when you've no interest whatsoever in the historical development of our present understanding. Nevertheless, it pains me to see this kind of circular reasoning being foisted on today's students.)
3. If "it" refers to any OTHER planet orbiting the Sun, then Vijay is quite right. Kepler's "Third Law" was first deduced empirically, of course, but it is also a confirming expression of Newton's Law of Gravity. (Though one could argue that once again, the necessity of explaining the empirical Third Law in the context of Newton's Laws of Motion necessarily implied the global form that the Law of Gravity must have. [I say this because Newton had separately demonstrated that the elliptical orbit of any GIVEN planet required that IT was sampling an inverse square law for the RANGE of distance IT covered; but it's the tying up together of ALL the planets by the Third Law --- each one sampling PRECISELY THE SAME FORCE LAW with the same normalization involving the Sun's mass --- that made the "Law of Gravity" "UNIVERSAL."])
So, P^2 proportional to R^3 is all you need to work out the period of revolution of any OTHER planet; it's as much an expression of a theoretical consequence of the Law of Gravity as it is an expression of an observed empirical fact. (In fact, it was because Galileo noticed that Jupiter's 4 brightest moons --- now aka its "Galilean satellites" --- also satisfied a [differently normalized] P^2, a^3 relationship that he realised that they were orbiting Jupiter in a way that mimicked that of the full solar system. He took that to be some kind of "proof" of Copernican ideas, the Jovian system simply reflecting in microcosm what the larger system was doing, the clockwork within the larger clock. And you know what THAT idea got him --- house arrest for the last decade of his life!)
Live long and prosper.
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P.S. Postscript on "revolution" and "rotation."
"Revolution" and "rotation" are sometimes confused, perhaps not too surprisingly (rates of rotation are often measured as so many revolutions per unit of time)! This doesn't really matter in common discourse, but the two wordshave specific (and different) meanings to astronomers or astrophysicists. I find that the best way to keep them (technically) distinct is to think that the Earth ROTATES about its AXIS, but REVOLVES about the SUN.
This is essentially based on historical precedent, and may not do it for you. Recall that Copernicus's famous book was published as: "De revolutionibus orbium coelestium" or "On the Revolutions of the Heavenly Spheres" (implicitly carrying the planets along with them) But even that, I admit, could confuse, since you could argue in that example that it's the ROTATING spheres (with the planets embedded in them) which lead to the planets themselves REVOLVING! Heavens! (literally); let's face it, language has many pitfalls.
Nevertheless, we say that the Sun ROTATES about its AXIS (in a surface latitude dependent ~ 26-30 days, analogous to Earth's daily rotation), but REVOLVES about the centre of the MILKY WAY GALAXY (in ~ 250 million years, analogous to Earth's yearly trip around the Sun.)
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2006-12-01 14:52:05
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answer #1
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answered by Dr Spock 6
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Well, if you're asking for the period of solar revolution, it does not depend on the distance to earth, not to first order anyway. You would have to measure how fast some feature on it's surface moves such as a sun spot. By the way, the sun has bands that rotate at different rates.
2006-12-01 15:03:03
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answer #2
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answered by ZeedoT 3
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the first two answers seem to know what they are talking about but neither of them chose to include the different gravitational pulls of the planets. surely the position of the planets in relation to the object you wish to study would have an impact on the period of revolution. if you look at our solar system pluto actually comes closer than neptune twice on its eliptic path. haleys comet is on a 75year eliptic orbit of the sun and it passes by all the orbits of the other planets.
the first two answers may be right but it would be best to look at all the variables if you wish to gain an accurate answer.
another thing to keep in mind too is that some of the planets if not all in our solsr system are actually spiralling around the sun. i was reading the Murcury actually changes its axis to the sun by 1 degree every 100.000.000 years or so. by this it means that the true revolution may take 36.000.000.000 years.
we only think we know the answers to all these questions but in reality we don't KNOW anything.
2006-12-01 14:48:01
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answer #3
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answered by pleiades-im-coming-home 2
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You need also the gravitation force between earth and sun = mass-earth x velocity^2 / distance
2006-12-01 13:22:32
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answer #4
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answered by Sjors d 2
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well GMm/r^2 = mv^2/r where rw=v, where w is the angular frequency mrw^2 = GMm/r^2 w^2=GM/r^3 w=2pi*f T=1/f => T = (2pi)*sqrt(r^3/(GM)) is the period of revolution where r is the radius, G is the gravitational constant, and M is the mass of the planet
2016-03-13 01:30:21
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answer #5
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answered by Danielle 4
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Previous answer is partially right, the way to solve this is the following.
Centrifugal force = centripetal force (gravitational force)
(Mass of planet) (Speed of planet) (Speed of planet) / R = G. (Mass of sun) (Mass of planet) / R*R
To compute period of revelution we need to compute V, the velocity of the planet.
Solving the equation,
V = sqrt (G. mass of the sun /R)
Having found V, we can compute period as follows,
Length of one revelution = 2Pi R
Velocity = V
Time = 2 . Pi .R / V
Time = 2Pi R sqrt(R) /G (Mass of the sun)
(Note : G is gravitational constant 6.67 * 10 to the -11)
2006-12-01 13:31:25
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answer #6
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answered by Vijay 2
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measure the milky way
Ob1
The suns revolution surrounds the black hole of the milky way
i see no querie of planets here
2006-12-01 13:44:18
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answer #7
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answered by old_brain 5
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