gravitational orbit
111Tidal acceleration — is an effect of the tidal forces between an orbiting natural satellite ( i.e. a moon), and the planet (called the primary) that it orbits. It causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding …
112Asteroid-impact avoidance — Planetary defense redirects here. For defending against alien invasion in fiction, see alien invasion. Artist s impression of a major impact event. The collision between Earth and an asteroid a few kilometres in diameter releases as much energy… …
113Apache Point Observatory Lunar Laser-ranging Operation — APOLLO shooting a laser at the Moon. The laser pulse is reflected from the retroreflectors on the Moon (see below) and returned to the telescope. The round trip time tells the distance to the Moon to great accuracy. In this picture the Moon is… …
114Interplanetary spaceflight — or interplanetary travel is travel between planets within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Current achievements in interplanetary travel Remotely… …
115Orbital resonance — For the science fiction novel by John Barnes, see Orbital Resonance (novel). In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their… …
116Solar sail — Solar sails (also called light sails or photon sails, especially when they use light sources other than the Sun) are a proposed form of spacecraft propulsion using large membrane mirrors. Radiation pressure is about 10 5 Pa at Earth s distance… …
117Newton's law of universal gravitation — Classical mechanics Newton s Second Law History of classical mechanics  …
118Einstein–Cartan theory — in theoretical physics extends general relativity to correctly handle spin angular momentum. As the master theory of classical physics general relativity has one known flaw: it cannot describe spin orbit coupling , i.e., exchange of intrinsic… …
119Space geostrategy — Geostrategy in space (also referred to as astrostrategy) deals with the strategic considerations of location and resources in outer space territory. In essence, it is the study of the strategic application of resources to the geography of space.… …
120atom — /at euhm/, n. 1. Physics. a. the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical… …
