 Two bodies with a slight difference in mass orbiting around a common barycenter. The sizes, and this particular type of orbit are similar to the Pluto- Charon system. In physics, an orbit is the path that an object makes around another object while under the influence of a source of centripetal force, such as gravity. Image File history File links Two bodies with a slight difference in mass orbiting around a common barycenter (red cross) with circular orbits. ...
Image File history File links Two bodies with a slight difference in mass orbiting around a common barycenter (red cross) with circular orbits. ...
Mass is a property of a physical object that quantifies the amount of matter and energy it contains. ...
It has been suggested that Center of gravity be merged into this article or section. ...
Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ...
Media:Example. ...
Physics (from the Greek, φυσικός (physikos), natural, and φÏσις (physis), nature) is the science of the natural world, which deals with the fundamental constituents of the universe, the forces they exert on one another, and the results of these forces. ...
An object that moves in a circular path undergoes a continuous acceleration towards the center of the circle. ...
Gravity is a force of attraction that acts between bodies that have mass. ...
History
Orbits were first analyzed mathematically by Johannes Kepler who formulated his results in his three laws of planetary motion. First, he found that the orbits of the planets in our solar system are elliptical, not circular (or epicyclic), as had previously been believed, and that the sun is not located at the center of the orbits, but rather at one focus. Second, he found that the orbital speed of each planet is not constant, as had previously been thought, but rather that the speed of the planet depends on the planet's distance from the sun. And third, Kepler found a universal relationship between the orbital properties of all the planets orbiting the sun. For each planet, the cube of the planet's distance from the sun, measured in astronomical units (AU), is equal to the square of the planet's orbital period, measured in Earth years. Jupiter, for example, is approximately 5.2 AU from the sun and its orbital period is 11.86 Earth years. So 5.2 cubed equals 11.86 squared, as predicted. Johannes Kepler Johannes Kepler (December 27, 1571 – November 15, 1630), a key figure in the scientific revolution, was a German mathematician, astrologer, astronomer, and an early writer of science fiction stories. ...
Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...
A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star. ...
The solar system comprises the Earths Sun and the retinue of celestial objects gravitationally bound to it. ...
The ellipse and some of its mathematical properties. ...
In Euclidean geometry, a circle is the set of all points in a plane at a fixed distance, called the radius, from a fixed point, the centre. ...
In the Ptolemaic system of astronomy, the epicycle (literally: on the cycle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. ...
In geometry, the focus (pl. ...
The astronomical unit (AU or au or a. ...
Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies responding to the force of gravity were conic sections. Newton showed that a pair of bodies follow orbits of dimensions that are in inverse proportion to their masses about their common center of mass. Where one body is much more massive than the other, it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body. Sir Isaac Newton, President of the Royal Society, (4 January 1643 – 31 March 1727) [OS: 25 December 1642 – 20 March 1727] was an English mathematician, physicist, astronomer, alchemist, chemist, inventor, and natural philosopher who is generally regarded as one of the most influential scientists and mathematicians in history. ...
In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. ...
Types of conic sections Table of conics, Cyclopaedia, 1728 In mathematics, a conic section (or just conic) is a curve formed by intersecting a cone (more precisely, a right circular conical surface) with a plane. ...
Mass is a property of a physical object that quantifies the amount of matter and energy it contains. ...
It has been suggested that this article or section be merged with Center of gravity. ...
Planetary orbits Within a planetary system, planets, asteroids, comets and space debris orbit the central star in elliptical orbits. Any comet in a parabolic or hyperbolic orbit about the central star is not gravitationally bound to the star and therefore is not considered part of the star's planetary system. To date, no comet has been observed in our solar system with a distinctly hyperbolic orbit. Bodies which are gravitationally bound to one of the planets in a planetary system, either natural or artificial satellites, follow orbits about that planet. An artists concept of a protoplanetary disk. ...
A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star. ...
An asteroid is a small, solid object in our Solar System, orbiting the Sun. ...
Comet Hale-Bopp For other uses, see Comet (disambiguation). ...
Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any useful purpose. ...
The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...
In astrodynamics or celestial mechanics a elliptic orbit is an orbit with the eccentricity greater than 0 and less than 1. ...
Wikisource has an original article from the 1911 Encyclopædia Britannica about: Parabola A parabola The parabola (from the Greek: παÏαβολή) is a conic section generated by the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface. ...
A graph of a hyperbola, where h = k = 0 and a = b = 2. ...
The solar system comprises the Earths Sun and the retinue of celestial objects gravitationally bound to it. ...
Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ...
A satellite is any object that orbits another object (which is known as its primary). ...
Due to mutual gravitational perturbations, the eccentricities of the orbits of the planets in our solar system vary over time. Pluto and Mercury, the two smallest planets in the Solar System, have the most eccentric orbits. At the present epoch, Mars has the next largest eccentricity while the smallest eccentricities are those of the orbits of Venus and Neptune. In astrodynamics, under standard assumptions any orbit must be of conic section shape. ...
Atmospheric characteristics Atmospheric pressure 0. ...
Note: This article contains special characters. ...
Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...
(*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ...
Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ...
As an object orbits another, the periapsis is that point at which the two objects are closest to each other and the apoapsis is that point at which they are the farthest from each other. This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...
A spatial point is an entity with a location in space but no extent (volume, area or length). ...
This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...
In the elliptical orbit, the centre of mass of the orbiting-orbited system will sit at one focus of both orbits, with nothing present at the other focus. As a planet approaches periapsis, the planet will increase in velocity. As a planet approaches apoapsis, the planet will decrease in velocity. The center of mass or center of inertia of an object is a point at which the objects mass can be assumed, for many purposes, to be concentrated. ...
In geometry, the focus (pl. ...
The velocity of an object is simply its speed in a particular direction. ...
See also: Kepler's laws of planetary motion Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...
Understanding orbits There are a few common ways of understanding orbits. - As the object moves sideways, it falls toward the orbited object. However it moves so quickly that the curvature of the orbited object will fall away beneath it.
- A force, such as gravity, pulls the object into a curved path as it attempts to fly off in a straight line.
- As the object falls, it moves sideways fast enough (has enough tangential velocity) to miss the orbited object. This understanding is particularly useful for mathematical analysis, because the object's motion can be described as the sum of the three one-dimensional coordinates oscillating around a gravitational center.
As an illustration of the orbit around a planet (eg Earth), the much-used cannon model may prove useful (see image below). Imagine a cannon sitting on top of a (very) tall mountain, which fires a cannonball horizontally. The mountain needs to be very tall, so that the cannon will be above the Earth's atmosphere and we can ignore the effects of air friction on the cannon ball. Look up path in Wiktionary, the free dictionary. ...
Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ...
 Illustration of Orbits using Cannonballs I created this drawing myself - FrankH 06:31, 12 Jan 2005 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...
If the cannon fires its ball with a low initial velocity, the trajectory of the ball will curve downwards and hit the ground (A). As the firing velocity is increased, the cannonball will hit the ground further (B) and further (C) away from the cannon, because while the ball is still falling towards the ground, the ground is curving away from it (see first point, above). If the cannonball is fired with sufficient velocity, the ground will curve away from the ball at the same rate as the ball falls — it is now in orbit (D). The orbit may be circular like (D) or if the firing velocity is increased even more, the orbit may become more (E) and more (F) elliptical. At a certain even faster velocity (called the escape velocity) the motion changes from an elliptical orbit to a hyperbola. The ellipse and some of its mathematical properties. ...
In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a...
A graph of a hyperbola, where h = k = 0 and a = b = 2. ...
Newton's laws of motion For a system of only two bodies that are only influenced by their mutual gravity, their orbits can be exactly calculated by Newton's laws of motion and gravity. Briefly, the sum of the forces will equal the mass times its acceleration. Gravity is proportional to mass, and falls off proportionally to the square of distance.
To calculate, it is convenient to describe the motion in a coordinate system that is centered on the heavier body, and we can say that the lighter body is in orbit around the heavier body. In mathematics as applied to geometry, physics or engineering, a coordinate system is a system for assigning a tuple of numbers to each point in an n-dimensional space. ...
An unmoving body that's far from a large object has more energy than one that's close. This is because it can fall farther. This is called "potential energy" because it is not yet actual.
With two bodies, an orbit is a flat curve. The orbit can be open (so the object never returns) or closed (returning), depending on the total kinetic + potential energy of the system. In the case of an open orbit, the speed at any position of the orbit is at least the escape velocity for that position, in the case of a closed orbit, always less. Kinetic jkljfkdffmdklcjenergy (SI unit: the [[klof its motion. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a...
The path of a free-falling (orbiting) body is always a conic section. Free Fall opens with one of the most stunning first paragraphs I have ever, or am ever likely to, read. ...
Types of conic sections Table of conics, Cyclopaedia, 1728 In mathematics, a conic section (or just conic) is a curve formed by intersecting a cone (more precisely, a right circular conical surface) with a plane. ...
An open orbit has the shape of a hyperbola (or in the limiting case, a parabola); the bodies approach each other for a while, curve around each other around the time of their closest approach, and then separate again forever. This may be the case with comets that occasionally approach the Sun. A graph of a hyperbola, where h = k = 0 and a = b = 2. ...
Wikisource has an original article from the 1911 Encyclopædia Britannica about: Parabola A parabola The parabola (from the Greek: παÏαβολή) is a conic section generated by the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface. ...
Comet Hale-Bopp For other uses, see Comet (disambiguation). ...
A closed orbit has the shape of an ellipse (or in the limiting case, a circle). The point where the orbiting body is closest to Earth is the perigee, called periapsis (less properly, "perifocus" or "pericentron") when the orbit is around a body other than Earth. The point where the satellite is farthest from Earth is called apogee, apoapsis, or sometimes apifocus or apocentron. A line drawn from periapsis to apoapsis is the line-of-apsides. This is the major axis of the ellipse, the line through its longest part. The ellipse and some of its mathematical properties. ...
In Euclidean geometry, a circle is the set of all points in a plane at a fixed distance, called the radius, from a fixed point, the centre. ...
This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...
This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...
Orbiting bodies in closed orbits repeat their path after a constant period of time. This motion is described by the empirical laws of Kepler, which can be mathematically derived from Newton's laws. These can be formulated as follows: Johannes Kepler Johannes Kepler (December 27, 1571 – November 15, 1630), a key figure in the scientific revolution, was a German mathematician, astrologer, astronomer, and an early writer of science fiction stories. ...
- The orbit of a planet around the Sun is an ellipse, with the Sun in one of the focal points of the ellipse. Therefore the orbit lies in a plane, called the orbital plane. The point on the orbit closest to the attracting body is the periapsis. The point farthest from the attracting body is called the apoapsis. There are also specific terms for orbits around particular bodies; things orbiting the Sun have a perihelion and aphelion, things orbiting the Earth have a perigee and apogee, and things orbiting the Moon have a perilune and apolune (or, synonymously, periselene and aposelene). An orbit around any star, not just the Sun, has a periastron and an apastron
- As the planet moves around its orbit during a fixed amount of time, the line from Sun to planet sweeps a constant area of the orbital plane, regardless of which part of its orbit the planet traces during that period of time. This means that the planet moves faster near its perihelion than near its aphelion, because at the smaller distance it needs to trace a greater arc to cover the same area. This law is usually stated as "equal areas in equal time."
- For each planet, the ratio of the 3rd power of its semi-major axis to the 2nd power of its period is the same constant value for all planets.
Except for special cases like Lagrangian points, no method is known to solve the equations of motion for a system with four or more bodies. The 2-body solutions were published by Newton in Principia in 1687. In 1912, K. F. Sundman developed a converging infinite series that solves the 3-body problem, however it converges too slowly to be of much use. Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ...
The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...
A contour plot of the effective potential of a two-body system (the Sun and Earth here), showing the 5 Lagrange points. ...
Newtons own copy of his Principia, with hand written corrections for the second edition. ...
Instead, orbits can be approximated with arbitrarily high accuracy. These approximations take two forms.
One form takes the pure elliptic motion as a basis, and adds perturbation terms to account for the gravitational influence of multiple bodies. This is convenient for calculating the positions of astronomical bodies. The equations of motion of the moon, planets and other bodies are known with great accuracy, and are used to generate tables for celestial navigation. Perturbation is a term used in astronomy to describe alterations to an objects orbit caused by gravitational interactions with other bodies. ...
Celestial Navigation is the 15th episode of The West Wing. ...
The differential equation form is used for scientific or mission-planning purposes. According to Newton's laws, the sum of all the forces will equal the mass times its acceleration (F = ma). Therefore accelerations can be expressed in terms of positions. The perturbation terms are much easier to describe in this form. Predicting subsequent positions and velocities from initial ones corresponds to solving an initial value problem. Numerical methods calculate the positions and velocities of the objects a tiny time in the future, then repeat this. However, tiny arithmetic errors from the limited accuracy of a computer's math accumulate, limiting the accuracy of this approach. Graph of a differential equation In mathematics, a differential equation is an equation in which the derivatives of a function appear as variables. ...
In mathematics, an initial value problem is a statement of a differential equation together with specified value of the unknown function at a given point in the domain of the solution. ...
Differential simulations with large numbers of objects perform the calculations in a hierarchical pairwise fashion between centers of mass. Using this scheme, galaxies, star clusters and other large objects have been simulated.
Analysis of orbital motion (see also orbit equation and Kepler's first law) In astrodynamics an orbit equation defines the path of orbiting body around central body relative to , without specifying position as a function of time. ...
Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...
To analyze the motion of a body moving under the influence of a force which is always directed towards a fixed point, it is convenient to use polar coordinates with the origin coinciding with the centre of force. In such coordinates the radial and transverse components of the acceleration are, respectively: This article describes some of the common coordinate systems that appear in elementary mathematics. ...
Acceleration is the time rate of change of velocity, and at any point on a v-t graph, it is given by the slope of the tangent to that point In physics, acceleration (symbol: a) is defined as the rate of change (or derivative with respect to time) of velocity. ...
 and  . Since the force is entirely radial, and since acceleration is proportional to force, it follows that the transverse acceleration is zero. As a result,  . After integrating, we have  The constant of integration l is the angular momentum per unit mass. It then follows that  where we have introduced the auxiliary variable  . The radial force is f(r) per unit is ar, then the elimination of the time variable from the radial component of the equation of motion yields:  . In the case of gravity, Newton's law of universal gravitation states that the force is proportional to the inverse square of the distance: Gravity is a force of attraction that acts between bodies that have mass. ...
Gravity is a force of attraction that acts between bodies that have mass. ...
 where G is the constant of universal gravitation, m is tha mass of the orbiting body (planet), and M is the mass of the central body (the Sun). Substituting into the prior equation, we have According to the law of universal gravitation, the attractive force between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. ...
 . So for the gravitational force – or, more generally, for any inverse square force law – the right hand side of the equation becomes a constant and the equation is seen to be the harmonic equation (up to a shift of origin of the dependent variable). A harmonic oscillator is a system which, when displaced from its equilibrium position, experiences a restoring force proportional to the displacement : where is a positive constant. ...
The equation of the orbit described by the particle is thus:
 , where p, e and θ0are constants of integration,  If parameter e is smaller than one, e is the eccentricity and a the semi-major axis of an ellipse. In gerneral, this can be recognized as the equation of a conic section in polar coordinates (r,θ). In astrodynamics, under standard assumptions any orbit must be of conic section shape. ...
The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ...
The ellipse and some of its mathematical properties. ...
Types of conic sections Table of conics, Cyclopaedia, 1728 In mathematics, a conic section (or just conic) is a curve formed by intersecting a cone (more precisely, a right circular conical surface) with a plane. ...
This article describes some of the common coordinate systems that appear in elementary mathematics. ...
Orbital period See: orbital period The orbital period is the time it takes a planet (or another object) to make one full orbit. ...
Orbital decay If some part of a body's orbit enters an atmosphere, its orbit can decay because of drag. At each periapsis, the object scrapes the air, losing energy. Each time, the orbit grows less eccentric (more circular) because the object loses kinetic energy precisely when that energy is at its maximum. Eventually, the orbit circularises and then the object spirals into the atmosphere. It has been suggested that Drag equation be merged into this article or section. ...
The bounds of an atmosphere vary wildly. During solar maxima, the Earth's atmosphere causes drag up to a hundred kilometres higher than during solar minimums. Solar maximum or solar max is the period of greatest solar activity in the solar cycle of the sun. ...
Some satellites with long conductive tethers can also decay because of electromagnetic drag from the Earth's magnetic field. Basically, the wire cuts the magnetic field, and acts as a generator. The wire moves electrons from the near vacuum on one end to the near-vacuum on the other end. The orbital energy is converted to heat in the wire. The magnetosphere shields the surface of the Earth from the charged particles of the solar wind. ...
Another method of artificially influencing an orbit is through the use of solar sails or magnetic sails. These forms of propulsion require no propellant or energy input, and so can be used indefinitely. See statite for one such proposed use. Concept image of a solar sail spacecraft in the process of unfurling sails. ...
A magnetic sail or magsail is a proposed method of spacecraft propulsion. ...
A statite is a hypothetical type of artificial satellite that employs a solar sail to continuously modify its orbit in ways that gravity alone would not allow. ...
Orbital decay can also occur due to tidal forces for objects below the synchronous orbit for the body they're orbiting. The gravity of the orbiting object raises tidal bulges in the primary, and since below the synchronous orbit the orbiting object is moving faster than the body's surface the bulges lag a short angle behind it. The gravity of the bulges is slightly off of the primary-satellite axis and thus has a component along the satellite's motion. The near bulge slows the object more than the far bulge speeds it up, and as a result the orbit decays. Conversely, the gravity of the satellite on the bulges applies torque on the primary and speeds up its rotation. Artificial satellites are too small to have an appreciable tidal effect on the planets they orbit, but several moons in the solar system are undergoing orbital decay by this mechanism. Mars' innermost moon Phobos is a prime example, and is expected to either impact Mars' surface or break up into a ring within 50 million years. Comet Shoemaker-Levy 9 after breaking up under the influence of Jupiters tidal forces. ...
A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body. ...
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. ...
In physics, torque can be thought of informally as rotational force. Torque is commonly measured in units of newton metres; although, centiNewton Meters (cNm), Foot Pounds (Lb-Ft), Inch Pounds (Lb-In) and Inch Ounces (Oz-In) are also frequently used expressions of torque. ...
Phobos (IPA , Greek Φόβος: Fright), is the larger and innermost of Mars two moons, and is named after Phobos, son of Ares (Mars) from Greek Mythology. ...
Finally, orbits can decay via the emission of gravitational waves. This mechanism is extremely weak for most stellar objects, only becoming significant in cases where there is a combination of extreme mass and extreme acceleration, such as with black holes or neutron stars that are orbiting each other closely. In physics, gravitational radiation is energy that is transmitted through waves in the gravitational field of space-time, according to Albert Einsteins theory of general relativity: The Einstein field equations imply that any accelerated mass radiates energy this way, in the same way as the Maxwell equations that any...
A black hole is a concentration of mass great enough that the force of gravity prevents anything past its event horizon from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). ...
A neutron star is one of the few possible endpoints of stellar evolution. ...
Earth orbits See Earth orbit for more details. Earth orbit is an orbit around the planet Earth. ...
(this is not a complete list). A low Earth orbit (LEO) is an orbit in which objects such as satellites are below intermediate circular orbit (ICO) and far below geostationary orbit, but typically around 350 - 1400 km above the Earths surface. ...
Highly Elliptical Orbit (HEO) (often incorrectly referred to as the Molniya orbit after the former Soviet communications satellite network which used a HEO orbit) is a satelite orbit characterized by a relatively low-altitude perigee and an extremely high-altitude apogee. ...
Intermediate circular orbit (ICO), also called medium earth orbit (MEO), is used by satellites between the altitudes of low earth orbit (up to 1400 km) and geostationary orbit (ca. ...
A geostationary orbit (GSO) is a circular orbit directly above the Earths equator (0º latitude). ...
A geosynchronous orbit is a geocentric orbit that has the same orbital period as the sidereal rotation period of the Earth. ...
A geostationary transfer orbit (GTO) is a Hohmann transfer orbit around the Earth between a low Earth orbit (LEO) and a geostationary orbit (GEO). ...
Molniya orbit is a class of a highly elliptic orbit with inclination of +/-63. ...
A satellite in a polar orbit passes above or nearly above both poles of the planet (or other celestial body) on each revolution. ...
A polar sun synchronous orbit is a nearly polar orbit. ...
Scaling in gravity The gravitational constant G is measured to be: According to the law of universal gravitation, the attractive force between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. ...
- (6.6742 ± 0.001) × 10−11 N·m2/kg2
- (6.6742 ± 0.001) × 10−11 m3/(kg·s2)
- (6.6742 ± 0.001) × 10−11 (kg/m3)-1s-2.
Thus the constant has dimension density-1 time-2. This corresponds to the following properties.
Scaling of distances (including sizes of bodies, while keeping the densities the same) gives similar orbits without scaling the time: if for example distances are halved, masses are divided by 8, gravitational forces by 16 and gravitational accelerations by 2. Hence orbital periods remain the same. Similarly, when an object is dropped from a tower, the time it takes to fall to the ground remains the same with a scale model of the tower on a scale model of the earth. Several equivalence relations in mathematics are called similarity. ...
When all densities are multiplied by four, orbits are the same, but with orbital velocities doubled.
When all densities are multiplied by four, and all sizes are halved, orbits are similar, with the same orbital velocities.
These properties are illustrated in the formula
 for an elliptical orbit with semi-major axis a, of a small body around a spherical body with radius r and average density σ, where T is the orbital period. The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ...
Role in the evolution of atomic theory When atomic structure was first probed experimentally early in the twentieth century, an early picture of the atom portrayed it as a miniature solar system bound by the coulomb force rather than by gravity. This was inconsistent with electrodynamics and the model was progressively refined as quantum theory evolved, but there is a legacy of the picture in the term orbital for the wave function of an energetically bound electron state. Properties In chemistry and physics, an atom (Greek άτομον meaning indivisible) is the smallest possible particle of a chemical element that retains its chemical properties. ...
In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrostatic force that one stationary, electrically charged object of small dimensions (ideally, a point source) exerts on another. ...
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...
Fig. ...
Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ...
See also Astrojax Plus Astrojax is a childrens toy consisting of three balls on a string--a ball is fixed at each end of the string, and the center ball is free to slide along the string between the two end balls. ...
In astrodynamics or celestial mechanics a circular orbit is an elliptic orbit with the eccentricity equal to 0. ...
A geostationary orbit (abbreviated GEO) is a circular orbit in the Earths equatorial plane, any point on which revolves about the Earth in the same direction and with the same period as the Earths rotation. ...
There sometimes appears to be confusion among the general public about the difference between sub-orbital and orbital spaceflights. ...
Two bodies with similar mass orbiting around a common barycenter with elliptic orbits. ...
In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a...
A geostationary orbit (GSO) is a circular orbit directly above the Earths equator (0º latitude). ...
Gravity is a force of attraction that acts between bodies that have mass. ...
It has been suggested that sling effect be merged into this article or section. ...
In astronautics and aerospace engineering, the Hohmann transfer orbit is an orbital maneuver that moves a spacecraft from one orbit to another using the lowest possible delta-v for the specific transfer. ...
In astrodynamics or celestial mechanics a hyperbolic trajectory is an orbit with the eccentricity greater than 1. ...
Artists concept of the Interplanetary Transport Network. ...
Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...
Milankovitch cycles are the collective effect of changes in the Earths movements upon its climate, named after Serbian geophysicist Milutin Milanković. The eccentricity, axial tilt, and precession of the Earths orbit vary in several patterns, resulting in 100,000 year ice age cycles of the Quaternary glaciation over...
The n-body problem is the problem of finding, given the initial positions, masses, and velocities of n bodies, their subsequent motions as determined by classical mechanics, i. ...
In astrodynamics an orbit equation defines the path of orbiting body around central body relative to , without specifying position as a function of time. ...
An orbital maneuver is a change from one orbit to another, accomplished by applying thrust. ...
The orbital period is the time it takes a planet (or another object) to make one full orbit. ...
An orbital spaceflight (or orbital flight) in the general sense is a spaceflight where the trajectory of a spacecraft reaches the height of, and through having an appropriate velocity enters into, orbit around an astronomical body. ...
The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ...
In astrodynamics or celestial mechanics a parabolic trajectory is an orbit with the eccentricity equal to 1. ...
This article is about retrograde motion. ...
In astrodynamics the specific orbital energy (or vis-viva energy) of an orbiting body traveling through space under standard assumptions is the sum of its potential energy () and kinetic energy () per unit mass. ...
A sub-orbital spaceflight (or sub-orbital flight) is a spaceflight that does not involve putting a vehicle into orbit. ...
A trajectory is an imagined trace of positions followed by an object moving through space. ...
References - Abell, Morrison, and Wolff (1987). Exploration of the Universe, fifth edition, Saunders College Publishing.
External links - An on-line orbit plotter: http://www.bridgewater.edu/departments/physics/ISAW/PlanetOrbit.html
- Orbital Mechanics (Rocket and Space Technology)
- The NOAA page on Climate Forcing Data includes (calculated) data on Earth orbit variations over the last 50 million years and for the coming 20 million years
- The orbital simulations by Varadi, Ghil and Runnegar (2003) provide another, slightly different series for Earth orbit eccentricity, and also a series for orbital inclination. Orbits for the other planets were also calculated[1], but only the eccentricity data for Earth and Mercury are available online.
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