earth-centered orbit
11Deferent and epicycle — Deferent redirects here. For the acknowledgement of the legitimacy of the power of one s superior or superiors, see Deference. The basic elements of Ptolemaic astronomy, showing a planet on an epicycle (smaller dashed circle) , a deferent (larger …
12Precession (astronomy) — In astronomy, precession refers to the movement of the rotational axis of a body, such as a planet, with respect to inertial space. In particular, it refers to the precession of the Earth s rotational axis, also called the precession of the… …
13Vega — Starbox begin name=Vega Starbox image caption = Location of Vega in the constellation Lyra. Starbox observe epoch=J2000.0 constell=Lyra ra=RA|18|36|56.3364cite web author=Staff date=October 30, 2007 url=http://simbad.u strasbg.fr/simbad/sim… …
14Solar System — This article is about the Sun and its planetary system. For other systems, see planetary system and star system. For a list of physical and orbital statistics for the Solar System s largest bodies, see List of gravitationally rounded objects of… …
15Space-based solar power — Left: Part of the solar energy is lost on its way through the atmosphere by the effects of reflection and absorption. Right: Space based solar power systems convert sunlight to microwaves outside the atmosphere, avoiding these losses, and the… …
16Solar power satellite — A solar power satellite, or SPS or Powersat, as originally proposed would be a satellite built in high Earth orbit that uses microwave power transmission to beam solar power to a very large antenna on Earth. Advantages of placing the solar… …
17Formation and evolution of the Solar System — Artist s conception of a protoplanetary disk The formation and evolution of the Solar System is estimated to have begun 4.568 billion years ago with the gravitational collapse of a small part of a giant molecular cloud …
18Venus — This article is about the planet. For other uses, see Venus (disambiguation). Venus   …
193753 Cruithne — Discovery Discovered by Duncan Waldron Discovery date October 10, 1986 …
20Megastructure — Not to be confused with Superstructure. For other uses, see Megastructure (disambiguation). The Great Wall of China is a megastructure. This picture was taken near Beijing in winter. A megastructure is a very large manmade object, though the… …
