What is Orbital period: Definition and 86 Discussions

The orbital period (also revolution period) is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars.
For celestial objects in general the sidereal orbital period (sidereal year) is referred to by the orbital period, determined by a 360° revolution of one celestial body around another, e.g. the Earth orbiting the Sun, relative to the fixed stars projected in the sky. Orbital periods can be defined in several ways. The tropical period is more particular about the position of the parent star. It is the basis for the solar year, and respectively the calendar year.
The synodic period incorporates not only the orbital relation to the parent star, but also to other celestial objects, making it not a mere different approach to the orbit of an object around its parent, but a period of orbital relations with other objects, normally Earth and their orbits around the Sun. It applies to the elapsed time where planets return to the same kind of phenomena or location, such as when any planet returns between its consecutive observed conjunctions with or oppositions to the Sun. For example, Jupiter has a synodic period of 398.8 days from Earth; thus, Jupiter's opposition occurs once roughly every 13 months.
Periods in astronomy are conveniently expressed in various units of time, often in hours, days, or years. They can be also defined under different specific astronomical definitions that are mostly caused by the small complex external gravitational influences of other celestial objects. Such variations also include the true placement of the centre of gravity between two astronomical bodies (barycenter), perturbations by other planets or bodies, orbital resonance, general relativity, etc. Most are investigated by detailed complex astronomical theories using celestial mechanics using precise positional observations of celestial objects via astrometry.

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  1. K

    Orbital period and speed of a space shuttle in flight

    Homework Statement The space shuttle is in a 290-mile-high orbit. What is the shuttles orbital speed? Homework Equations v=√GM/R+h The Attempt at a Solution Period: Me= 5.98x10^24kg Re= 6.38x10^6m H= 290miles * 1609m = 466610m v= √(6.67x10^-11 N)(5.98x10^24 kg)/ (6.38x10^6...
  2. L

    What is the Orbital Period of Eris, the Tenth Planet?

    Homework Statement We will compute the orbit of Eris, the infamous \tenth planet" that caused Pluto to be demoted to \dwarf planet" status. Eris (also called 2003 UB313 in the textbook) has a semimajor axis a = 68:048 AU and eccentricity e = 0:4336 based on the best current observations...
  3. G

    What is the equation for calculating orbital period?

    Ok just a quick question trying to work out the orbital period of an asteroid around the sun which has an orbital period 4times that of the Earth which is 1.5*10^11m i worked out the radius of the asteroid to be 6*10^11 but can't find the equation for the orbital period. Does anyone know it...
  4. S

    Planetary Motion, calculation of orbital period

    Hi everyone, I'm really confused with a particular question: Homework Statement A space shuttle orbits the Earth at 6720 km from its centre. The gravitational field strength is 8.9N/kg. Calculate the shuttle's orbital period in minutes... Homework Equations g=4pi^2...
  5. I

    Exploring the Orbital Period of a Rod-Mass System

    Homework Statement I've worked through part (iv) of this problem, but I am not sure if I shown enough calculation. The most important parts of the question, to put it all in context: (i) The gravitational force on a body of mass m at a distance r from the Earth with mass mE. The time it...
  6. S

    Calculating the Orbital Period

    Homework Statement Calculate the Orbital Period for the following: Earth's orbit to the Sun. I get stuck towards the end. I must use Newton's second law and have the Universal Law of Gravitation equal the Centrifugal Force. Newton's gravitational constant: G= 6.67*10^-11 Nm^2/kg^2 Mass of...
  7. Ranku

    Orbital period decay and gravitational waves

    We know that the orbital period of binary stars decay due to the emission of gravity waves that carry away energy from the system. What is the form of the energy loss of the system: kinetic energy or potential energy?
  8. Ranku

    Orbital period decay and gravitational waves

    We know that the orbital period of binary stars decay due to the emission of gravity waves that carry away energy from the system. What is the form of the energy loss of the system: kinetic energy or potential energy?
  9. C

    Calculating Orbital Period from Semi-Major Axis Alone

    Homework Statement Is it possible to figure out the orbital period of an object with only the orbital radius given? --- It seems to be with the equations given too little information Homework Equations The Attempt at a Solution
  10. T

    Difficulty with orbital period

    Homework Statement Find the speed of an Earth satellite whose orbit is 400km above the Earth's surface. What is the period of the orbit. Homework Equations The first part was pretty easy. I used v=[(Gm)/r]^(1/2) to get the answer. The Attempt at a Solution For the first part, I...
  11. D

    Solving for Moon B's Orbital Period: A Homework Challenge

    Homework Statement Two moons orbit a planet in nearly circular orbits. Moon A has orbital radius r, and moon B has orbital radius 5r. Moon A takes 50 days to complete one orbit. How long does it take moon B to complete and orbit? Homework Equations Kepler's Third Law The...
  12. L

    Orbital Period and Velocity Question

    Homework Statement The space shuttle is in a 310 mile high orbit. What are the shuttle's orbital period, in minutes, and its speed? Homework Equations Period = 2(pi)r/v The Attempt at a Solution I can't figure out how to find the period without already having the velocity.
  13. S

    Find the distance from the sun to the planet known the orbital period problem

    Homework Statement the problem asks to find the distance from the sun to a planet. the only information the question gives the the orbital period of 27 years and asks for the answer in km. Homework Equations c= (2)(pi)(r) The Attempt at a Solution assuming the planet revolves...
  14. A

    Deriving Orbital Period with Kepler's & Taylor Expansions

    Homework Statement Use Kepler's Third Law and a Taylor expansion to derive the following approximation for the orbital period of a satellite in low Earth orbit with a constant height h above the surface of the Earth. h << R_earth : P \approx P_{0}(1+3h/2R_{e}) Homework Equations Kepler's...
  15. F

    Orbital period variation in binary system

    Homework Statement Using the conservation of angular momentum and Kelper's third law, show that the relative change in orbital period produced by mass transfer is given by 1/P * dP/dt = 3 dM1/dt * (M1 - M2)/(M1M2) Homework Equations L = mu * sqrt(GMa) P^2 = (4*PI^2)/(G(M1+M2)) * a^3...
  16. I

    Orbital Period of Apollo Mission

    Homework Statement On each of the apollo missions the command module was placed in a very low aprox circular orbit above the moon. Assum the avrg hieght was 60km above surface of moon and moons radius is 7738km. (Mass of moon=7.34x10^22kg) What was the command modules orbital period...
  17. I

    Orbital period questions continued

    Homework Statement A 9.0x10^3kg satellite with an orbital radius of 3.20x10^7m orbits the Earth at an altitude of 2.56x10^7m. What is the orbital period?Homework Equations ΣFc = mac Kepler's third law equationThe Attempt at a Solution For this question I know that it is asking me to find the...
  18. I

    Calculating Mars' Orbital Period in Earth Years

    Homework Statement Mars orbits the sun at 1.52 Earth's orbital radius. What is the period of Mars in Earth years? Homework Equations ΣFc = mac The Attempt at a Solution I am unsure how to do this problem as this is the first "orbital period" question that I have encountered. Do I...
  19. R

    What Is the Correct Method to Calculate the Orbital Period of GPS Satellites?

    GPS (Global Positioning System) satellites orbit at an altitude of 2.0×10^7 m. Find the orbital period.(hours)I use the equation T=(2pi/sqrt(GM))r^(3/2). Shouldnt that be the correct way of doing it? I know I am supposed to add the altitude to the radius of the earth, G is known, M of Earth is...
  20. U

    Calculating Sputnik I's Orbital Period

    1.Sputnik I, the first artificial satellite to circle the planet (October 1957) had a mean orbital radius of 6957 km. Compute its period in seconds 2. I am using the equation T^2 = R^3/C 3. I converted 6957 km to AU's which equals 4.638 E-5. When I plug in the numbers, and convert...
  21. H

    Planet orbital period question

    Mars travels in a nearly circular orbit of radius 2.28 x 10^11 m around the Sun. The mass o Mars is 6.27 x 10^23 kg. The gravitational force of attraction between Mars and the sun has a magnitude of 1.63 x 10^21 N. a) what is the speed of Mars? i got 2.4 x 10^4 m/s b)Determine the period...
  22. P

    Calculate the orbital period of a spacecraft around the moon

    1. During an Apollo lunar landing mission, the command module continued to orbit the Moon at an altitude of 100km. How long did it take to go around the Moon once? 2. T= 2(pi)(r^3/2) / root (GM) mass of moon = 7.35 X 10^22 radius of moon= 1.74 X 10^6 3. I think that is the...
  23. J

    Finding distance of a planet whose orbital period is 2x Earth

    A small planet has an orbital period that is twice that of Earth. What is the planet's orbital distance? From Kepler's 3rd law of planetary motion, I can assume that: rp3 / rE3 = Tp2 / TE2 where rp is the orbital radius of the planet and Tp is the orbital period of the planet...
  24. W

    Hubble Space Telescope Orbital Period

    Use Kepler’s laws to determine the period of the Hubble Space Telescope which orbits the Earth at an altitude of 610 km. I'm using the equation i know to find the period of an object revolving around another object T^2=Kr^3 T^2=(4pi^2/GM)*r^3 G=6.67 x 10^-11 M=5.98× 10^24 (Mass of...
  25. P

    What is the Orbital Period of Jupiter in Earth Years?

    Jupiter is 5.2 times farther than Earth from the sun. Find Jupiter's orbital period in Earth years. Equation to use is: T^2 = Kr^3 Radius of Earth is 6378100 m and radius of Jupiter is 71492000 m. I rearrange the equation to K = T^2/r^3 and set k of Earth equal to k of Jupiter. I enter...
  26. D

    Revolving Around a Star: Calculating an Orbital Period

    A star has a mass approximately 100 times that of our sun. If a planet with the same mass as the Earth is oribiting at a radius similar to that of the Earth's radius around the sun, how long would it take the planet to revolve around the star once? Ok, the period of the Earth's rotation is...
  27. Saladsamurai

    Calculation for Asteroid Orbital Period

    Of an asteroid whose Mass is 2.0*10^-2 times that of Earth's and whose distance from the sun is twice the Earth's distance from the sun. Find the period in years. I am supposed to use the concept of gravitational F=centripital force=m\frac{v^2}{r} and the fact that v=\frac{2\pi r}{T} so this...
  28. R

    Temperature and orbital period

    Hi everyone, was hoping someone could help me to answer a question: an ateroid has an equilibrium temperature measured as 200 K. What is the object's orbital period around the Sun? That is the exact wording of that particular question and that's why I am a little stumped.. it also says...
  29. R

    Temperature and orbital period

    Homework Statement Hi everyone, was hoping someone could help me to answer a question: an ateroid has an equilibrium temperature measured as 200 K. What is the object's orbital period around the Sun? That is the exact wording of that particular question and that's why I am a little...
  30. P

    Exploring the Orbital Period of Circular Orbits around Black Holes

    Here's an interesting question inspired by a homework probem (not mine) - what is the orbital period (proper time) for someone in a circular orbit around a black hole as a function of the radius of their orbit (Schwarzschild r-coordinate). By setting the derivative of the effective potential to...
  31. DaveC426913

    How does the orbital diameter of 2003 UB313 compare to its orbital period?

    Is this true? (excerpted from http://www.astro.uni-bonn.de/~bertoldi/ub313/" about 2003 UB313) "...Its very elongated orbit takes it up to 97 times farther from the Sun than is the Earth - almost twice as far as the most distant point of Pluto's orbit – so that it takes twice as long as...
  32. A

    Calculating the Mass of a Star from a Planet's Orbital Period

    Suppose there is a planetary system in which a planet with an average distance of 6 AU from the star has an orbital period of 3 years. What is the mass of the star? The answer should be in SOLAR MASSES. I tried to use the formula: P^2 = (4pi^2*a^3)/G(m+M) but it didnt work:( any...
  33. B

    The square of an orbital period

    this is the expression ofr the orbital period T= 2*pi*R^(3/2)/sqrt(G*M) that i found now the next question asks me to find an expression for T^2=?
  34. J

    Approximate orbital period for earth's moon

    Does anyone know what would be the approximate orbital period (time for one complete orbit) for an apple placed in orbit around Earth at the moon’s distance from Earth?
  35. T

    Help with Calculating Planet's Orbital Period

    hi, could someone please help me with this problem?? If a small planet were discovered with a distance from the sun eight times that of the Earth, what would you predict for its period in (Earth) years. (i.e. how many times longer would it take to go round the sun than the Earth does.)
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