Related Research Articles
General Motors (GM), formally the General Motors Company, is an American multinational automotive manufacturing company headquartered in Detroit, Michigan, United States. By sales, it was the largest automaker in the United States in 2022, and was the largest in the world for 77 years before losing the top spot to Toyota in 2008.
In celestial mechanics, the Lagrange points are points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies. Mathematically, this involves the solution of the restricted three-body problem.
In celestial mechanics, escape velocity or escape speed is the minimum speed needed for a free, non-propelled object to escape from the gravitational influence of a primary body, thus reaching an infinite distance from it. It is typically stated as an ideal speed, ignoring atmospheric friction. Although the term "escape velocity" is common, it is more accurately described as a speed than a velocity because it is independent of direction. The escape speed is independent of the mass of the escaping object, but increases with the mass of the primary body; it decreases with the distance from the primary body, thus taking into account how far the object has already traveled. Its calculation at a given distance means that no acceleration is further needed for the object to escape: it will slow down as it travels—due to the massive body's gravity—but it will never quite slow to a stop. On the other hand, an object already at escape speed needs slowing for it to be captured by the gravitational influence of the body.
The gravitational binding energy of a system is the minimum energy which must be added to it in order for the system to cease being in a gravitationally bound state. A gravitationally bound system has a lower gravitational potential energy than the sum of the energies of its parts when these are completely separated—this is what keeps the system aggregated in accordance with the minimum total potential energy principle.
The orbital period is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit.
Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal gravitation. Orbital mechanics is a core discipline within space-mission design and control.
In gravitationally bound systems, the orbital speed of an astronomical body or object is the speed at which it orbits around either the barycenter or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.
The astronomical system of units, formerly called the IAU (1976) System of Astronomical Constants, is a system of measurement developed for use in astronomy. It was adopted by the International Astronomical Union (IAU) in 1976 via Resolution No. 1, and has been significantly updated in 1994 and 2009.
In classical mechanics, the gravitational potential at a point in space is equal to the work per unit mass that would be needed to move an object to that point from a fixed reference point. It is analogous to the electric potential with mass playing the role of charge. The reference point, where the potential is zero, is by convention infinitely far away from any mass, resulting in a negative potential at any finite distance.
The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. It is sometimes termed the Roche sphere. It was defined by the American astronomer George William Hill, based on the work of the French astronomer Édouard Roche.
Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or components of any binary system. If left unchecked, the decay eventually results in termination of the orbit when the smaller object strikes the surface of the primary; or for objects where the primary has an atmosphere, the smaller object burns, explodes, or otherwise breaks up in the larger object's atmosphere; or for objects where the primary is a star, ends with incineration by the star's radiation. Collisions of stellar-mass objects are usually accompanied by effects such as gamma-ray bursts and detectable gravitational waves.
Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events as measured by observers situated at varying distances from a gravitating mass. The lower the gravitational potential, the slower time passes, speeding up as the gravitational potential increases. Albert Einstein originally predicted this effect in his theory of relativity and it has since been confirmed by tests of general relativity.
In celestial mechanics, the standard gravitational parameterμ of a celestial body is the product of the gravitational constant G and the mass M of the bodies. For two bodies the parameter may be expressed as G(m1+m2), or as GM when one body is much larger than the other:
In astrodynamics, the characteristic energy is a measure of the excess specific energy over that required to just barely escape from a massive body. The units are length2 time−2, i.e. velocity squared, or energy per mass.
In celestial mechanics, a horseshoe orbit is a type of co-orbital motion of a small orbiting body relative to a larger orbiting body. The osculating (instantaneous) orbital period of the smaller body remains very near that of the larger body, and if its orbit is a little more eccentric than that of the larger body, during every period it appears to trace an ellipse around a point on the larger object's orbit. However, the loop is not closed but drifts forward or backward so that the point it circles will appear to move smoothly along the larger body's orbit over a long period of time. When the object approaches the larger body closely at either end of its trajectory, its apparent direction changes. Over an entire cycle the center traces the outline of a horseshoe, with the larger body between the 'horns'.
In physics and classical mechanics, the three-body problem is the problem of taking the initial positions and velocities of three point masses and solving for their subsequent motion according to Newton's laws of motion and Newton's law of universal gravitation. The three-body problem is a special case of the n-body problem. Unlike two-body problems, no general closed-form solution exists, as the resulting dynamical system is chaotic for most initial conditions, and numerical methods are generally required.
3360 Syrinx is an Apollo and Mars crosser asteroid discovered in 1981. It approaches Earth to within 40 Gm three times in the 21st century: 33 Gm in 2039, 40 Gm in 2070, and 24 Gm in 2085.
Explorer 33, also known as IMP-D and AIMP-1, was a spacecraft in the Explorer program launched by NASA on 1 July 1966 on a mission of scientific exploration. It was the fourth satellite launched as part of the Interplanetary Monitoring Platform series, and the first of two "Anchored IMP" spacecraft to study the environment around Earth at lunar distances, aiding the Apollo program. It marked a departure in design from its predecessors, IMP-A through IMP-C. Explorer 35 was the companion spacecraft to Explorer 33 in the Anchored IMP program, but Explorer 34 (IMP-F) was the next spacecraft to fly, launching about two months before AIMP-E, both in 1967.
3361 Orpheus is an Apollo asteroid that was discovered on 24 April 1982 by Carlos Torres at Cerro El Roble Astronomical Station. Its eccentric orbit crosses that of Mars and Earth, and approaches Venus as well. From 1900 to 2100 it passes closer than 30 Gm to Venus 11, Earth 33, and Mars 14 times. It passed by Earth at a distance of about 0.03 AU in 1937, 1978, 1982, and 2021 and will again in 2025.
References
- ↑ "2021 GM1". JPL Small-Body Database Lookup. Retrieved 2023-07-11.
 | This near-Earth asteroid-related article is a stub. You can help Wikipedia by expanding it. |