Apsis

An apsis (Greek: ἁψίς; plural apsides /ˈæpsdz/, Greek: ἁψίδες) is an extreme point in an object's orbit. The word comes via Latin from Greek and is cognate with apse. For elliptic orbits about a larger body, there are two apsides, named with the prefixes peri- (from περί (peri), meaning "near") and ap-, or apo- (from ἀπ(ό) (ap(ó)), meaning "away from") added to a reference to the thing being orbited.

  • For a body orbiting the Sun, the point of least distance is the perihelion (/ˌpɛrˈhliən/), and the point of greatest distance is the aphelion (/æpˈhliən/).
  • The terms become periastron and apastron when discussing orbits around other stars.
  • For any satellite of Earth including the Moon the point of least distance is the perigee (/ˈpɛr/) and greatest distance the apogee.
  • For any orbits around a center of mass, there are the terms pericenter and apocenter. Periapsis and apoapsis (or apapsis) are equivalent alternatives.
  • A straight line connecting the pericenter and apocenter is the line of apsides. This is the major axis of the ellipse, its greatest diameter. For a two-body system the center of mass of the system lies on this line at one of the two foci of the ellipse. When one body is sufficiently larger than the other it may be taken to be at this focus. However whether or not this is the case, both bodies are in similar elliptical orbits each having one focus at the system's center of mass, with their respective lines of apsides being of length inversely proportional to their masses. Historically, in geocentric systems, apsides were measured from the center of the Earth. However, in the case of the Moon, the center of mass of the Earth–Moon system, or Earth–Moon barycenter, as the common focus of both the Moon's and Earth's orbits about each other, is about 74% of the way from Earth's center to its surface.

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    Another Private Hell

    by: Abscess

    Don't want to go outside today
    Inside i think I'm gonna stay
    My tortured mind it chokes me down
    In here I'm free to bleed and drown
    Just one more private hell
    Stuck in this mental shell
    I haven't slept for seven days
    I watch my face just melt away
    I hear them coming after me
    Perpetual demonology...
    Brain in flames I'm sinking down
    Stabbing voices all around
    Sleep is something i can't do
    Stay awake, nightmares come true
    Just one more private hell
    Stuck in this mental shell
    I haven't slept for seven days
    I watch my face just melt away
    I hear them coming after me
    Perpetual demonology...
    Eyes are circles skeletonized
    Read Maldoror twenty five times
    Drank window cleaner and insect spray
    This hell is mine for one last day
    Just one more private hell
    Stuck in this mental shell
    I haven't slept for seven days
    I watch my face just melt away
    I hear them coming after me




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