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Topic: Libration


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In the News (Sun 16 Jun 19)

  
  WWU Planetarium - Lunar Libration
The lunar libration in latitude is due to the Moon's axis being slightly inclined relative to the Earth's axis.
The diurnal (daily) libration of the Moon is due to the observer first viewing from the western edge of the Earth as the Moon is rising, and then later from up to four thousand miles away to the east as the Moon is setting.
Libration of longitude is an effect of the Moon's varying rate of travel along its slightly elliptical orbit around the Earth.
www.wwu.edu /depts/skywise/lunar_libration.html   (355 words)

  
  Libration - Wikipedia, the free encyclopedia
In astronomy a libration (from the Latin verb libro -are "to balance, to sway", cf.
Libration in latitude is a consequence of the Moon's axis of rotation being slightly inclined to the normal to the plane of its orbit around Earth.
Libration in longitude is a consequence of the Moon's orbit around Earth being somewhat eccentric, so that the Moon's rotation sometimes leads and sometimes lags its orbital position.
en.wikipedia.org /wiki/Libration   (334 words)

  
 libration concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-10-12)
Libration is described as latitudinal, longitudinal and diurnal.
Physical librations are due to variations in the rate at which the Moon rotates on its axis.
The much larger optical librations are due to variations in the rate of the Moon's orbital motion, the obliquity of the Moon's equator to its orbital plane, and the diurnal changes of geometric perspective of an observer on the Earth's surface.
www.site.uottawa.ca:4321 /astronomy/libration.html   (215 words)

  
 Lunar Libration
There are also different kinds of libration: libration of longitude and libration of latitude.
Maximum librations are seen about one week AFTER perigee and one week AFTER apogee, revealing (depending upon the month) up to 8 degrees of longitude on the Moon's far side.
Libration of latitude, the north-south nodding, results primarily from the approximate 5 degree tilt of the Moon's orbital plane in respect to the ecliptic (Earth's orbital plane).
www.idialstars.com /luli.htm   (444 words)

  
 libration
Libration in latitude, a north-south nodding, is caused by the tilt of the Moon's rotation axis relative to its orbital plane.
Diurnal libration is an optical rather than a physical libration, amounting to less than 1°, and stems from the fact that, because of Earth's rotation, we view the Moon from different angles at moonrise and moonset.
Libration happens when an orbiting body is locked in a synchronous rotation; Mercury shows it, as do some other moons in the Solar System.
www.daviddarling.info /encyclopedia/L/libration.html   (248 words)

  
 Librations of the Moon
In the equilibrium position, the long axis of the Moon points towards Earth, and libration temporarily shifts the earth-pointing tip of that axis to the north, south, east or west.
"Libration" is used for any of several effects which allow us to "peek around the edge." Most of them, it turns out, are not associated with any pendulum-like motion of the axis, but rather represent a shift in viewing direction.
A third "libration" arises because the size of the Earth is not negligible.
www.phy6.org /stargaze/Smoon4.htm   (1693 words)

  
 EA6VQ - libration fading and the scattering properties of the lunar surface
I have heard libration fading on 432 take what should be a morse code dash sent at 15 WPM and turn it onto three dots (or 2 dots and a space).
One easy way to understand libration fading and estimate the QSB rate at a particular frequency is to model the patch of lunar surface that is reflecting most of the signal as a big antenna.
And there's more to libration fading than just us traveling through the speckle: the phase also changes on 'uplink', so the elemets of the 'phased array' on the Moon are fed with changing phases, and the speckle pattern itself moves and changes with about the same modulation rate.
www.vhfdx.net /discuss/libration.html   (3707 words)

  
 New 'Wave' In Space Exploration May Be Coming Soon
An orbit near a libration point is considered stable if a spacecraft in orbit needs little or no "station keeping," small nudges from positioning rockets to keep the craft on the right track.
"Libration points are located at places in the solar system where very interesting things are happening, such as the environment between the Earth and the sun," Howell says.
Between Jan. 6 and 10, two satellites in libration point orbits between the Earth and the sun, called SOHO and WIND, detected and recorded data from a major space "storm" that originated from a huge eruption on the sun.
www.eurekalert.org /pub_releases/1997-02/PU-NISE-040297.php   (1138 words)

  
 SeaWiFS Lunar Libration Effects   (Site not responding. Last check: 2007-10-12)
The libration effects arise from variations in the side of the Moon that faces the Earth during the lunar observations.
The libration effects are computed from linear regressions of the coordinates of the sub-spacecraft and sub-solar points on the lunar surface against the corrected lunar calibration time series.
The libration corrections are the inverse of the mean of the libration effects for bands 4 and 5.
oceancolor.gsfc.nasa.gov /SeaWiFS/On_Orbit/lcal/libration_effects.html   (74 words)

  
 Moon Libration
Longitude libration occurs from the Moon's synchronous rotation and elliptical orbit.
Latitude libration is the result of the Moon's equator being slightly tilted (1.5°) from its orbital plane and its orbital plane being tilted 5° from the ecliptic.
Diurnal libration is the result of the motion of the observer on Earth as the Earth rotates.
www.stargazing.net /david/moon/moonlibration.html   (267 words)

  
 ch9
The observations of the libration clouds reported by the OS0-6 satellite indicated that the clouds are of an angular size of approximately 6 degrees (compared to the 3.2-degree field of view of the Skylab instrument).
The areas investigated were generally 1 to 3 degrees away from the libration points, although in at least one observation the coverage was within 1 degree of....
It was calculated that the radiance contrast of a possible libration cloud composed of remaining candidate materials to the background zodiacal light would be maximized at about 30 degrees from the Sun (which was not within the field of view of the coronagraph).
history.nasa.gov /SP-401/ch9.htm   (897 words)

  
 Libration
Libration is the apparent side to side rocking and up and down nodding of the Moon.
A libration of 5 degrees in PA 1 means we are seeing more of the north area.
A libration of 5 degrees in PA 270 means we are seeing more of the “right” limb of the Moon, the side with Mare Crisium (as seen from the northern hemisphere).
www3.telus.net /public/aling/lunarcal/Help/190.htm   (863 words)

  
 HotBot Web Search for libration
Libration in latitude is due to the Moon's axis being slightly inclined relative to the Earth's.
This paper is to show some transfer orbits between the previously described libration orbits around L and the ones around L or vice versa.
Libration in latitude is a consequence of the Moon's axis of rotation being slightly inclined to the normal to the plane of its orbit around...
www.hotbot.com /inderelated8index.php?query=libration   (277 words)

  
 Libration - definition from Biology-Online.org
libration of the moon, any one of those small periodical changes in the position of the moons surface relatively to the earth, in consequence of which narrow portions at opposite limbs become visible or invisible alternately.
It receives different names according to the manner in which it takes place; as: (a) libration in longitude, that which, depending on the place of the moon in its elliptic orbit, causes small portions near the eastern and western borders alternately to appear and disappear each month.
(b) libration in latitude, that which depends on the varying position of the moons axis in respect to the spectator, causing the alternate appearance and disappearance of either pole.
www.biology-online.org /dictionary/Libration   (235 words)

  
 librazioni 1
With the librations we can to see regions of the Moon that are located beyond the edge of the boundary with the invisible hemisphere, with a latitude and longitude alternation.
With the longitude libration, a point located on the Moon surface during a lunation will shift alternatly by 8° to the east or west.
A consequence of this libration's effect is to trace a spiral curve inserted in a 10° circle, for every point located on the Moon's surface.
digilander.libero.it /gibbidomine/libration.html   (563 words)

  
 Lunar Libration - Wolfram Demonstration Project
Although the Moon is locked in orbit with the Earth, so that we only see one face from Earth, that face seems to wobble somewhat.
Libration of latitude occurs because the Moon's axis of rotation is not perpendicular to the plane of its orbit, so an observer in the northern hemisphere can sometimes see over the Moon's north pole and under its south pole.
Libration of longitude is caused by the eccentricity of the Moon's orbit, so an observer can sometimes see over the eastern and western edges of the Moon.
demonstrations.wolfram.com /LunarLibration   (119 words)

  
 Artemis Project: Lunar Orbital Libration
Latitudinal libration, due to the tilt of the moon's axis with respect to the ecliptic, will cause the Earth to oscillate north and south by 6.7 deg each way.
From the point of view of someone on Earth, longitudinal libration means we get a peek at the lunar farside 7.7 deg past 90 deg east and west longitude as it goes through its 29-day orbit about the Earth.
Diurnal libration, as seen from Earth due to rotation of the Earth, is 1 deg at western edge when moon is rising and 1 deg at eastern edge when moon is setting.
www.asi.org /adb/m/03/12/libration.html   (430 words)

  
 A Search for Natural or Artificial Objects Located at the Earth-Moon Libration Points
The sky positions of the triangular libration points and the four unique synodic halo points were computed using the American Ephemeris and Nautical Almanac 1979 at every hour during the planned observing periods in August-September 1979, and were interpolated to 1-min intervals to permit close digital tracking.
For particles initially at the triangular libration point L5 Schutz and Tapley (1970) found a progressive reduction in inclination from the mean lunar value of 5°.15 down to a lower limiting value of about 2° after 5000 days, a trend which they were unable to explain.
Roosen, R. A photographic investigation of the Gegenschein and the Earth-Moon libration point L5.
www.rfreitas.com /Astro/SearchIcarus1980.htm   (2347 words)

  
 L1 and Orbits
  A libration point is an equilibrium point in the gravitational and centripetal force field in a two-body system with a mass ratio of less than 0.0385 (Szebehely 266).
  Three of the libration points along the axis of the two bodies are known as collinear libration points.
Two types of orbits exist for collinear libration points; they are halo and lissajous orbits.
www.heavyhammer.com /clarkestation/orbit.shtml   (627 words)

  
 Surfing the Solar System - - science news articles online technology magazine articles Surfing the Solar System   (Site not responding. Last check: 2007-10-12)
Librate means to vibrate slightly, as a balance or a scale does before it settles down.
Put a satellite at a libration point and it would appear motionless from Earth, hanging in space as though the laws of gravity had been suspended.
Libration points are mathematical fictions, geometric fantasies, topological flights of fancy.
www.discover.com /issues/jun-99/features/featsolar/?page=1   (1611 words)

  
 LunarPhase Pro - Lunar Libration Diagram
At the left of the screen is a diagram showing the moon's libration over the course of the month.
The default plot (big yellow dots with little orange dots between them) shows the moon's topocentric libration for the month [topocentric means as seen from your location as specified in the Configuration screen].
The current moon diagram, with the yellow dot indicating the maximum libration point for the selected time and date is also included on the printout.
www.nightskyobserver.com /LunarPhaseCD/page16.html   (467 words)

  
 Libration
Diurnal libration is due to the observer being on the surface of the Earth, up to four thousand miles to one side of the Earth-Moon axis, a significant proportion of the centre-to-centre distance.
The difference in perspective between the rising and setting of the Moon appears as a slight turning of the Moon first to west and then to east.
Libration of longitude is an effect of the Moon's varying rate of travel along its slightly elliptical orbit.
www.inconstantmoon.com /not_libr.htm   (185 words)

  
 Computing the Libration Points
The libration points, also called the equilibrium or Lagrangian points, are solutions to the equations of motion for the spacecraft such that the x, y, and z positions and x, y, and z velocities are all 0.
To find the location of the 3 libration points lying on the earth-sun axis (L1, L2, and L3), one must solve for the x coordinate of each.
Once the libration points have been located, one can search for orbits about these points.
www.geom.uiuc.edu /~megraw/MATH1/lib.html   (308 words)

  
 SpaceViews Update 97 Feb 15: Technology
     Kathleen Howell, a professor in the aeronautics and astronautics department at Purdue, has found that libration points -- specific points in space formed by the interaction of the gravitational fields of the Sun, planets, and moons -- have two-dimensional "surfaces" associated with them.
     Libration points are already used by some spacecraft, such as the SOHO and WIND spacecraft, which use the L1 point between the Earth and the Sun to provide a stable location to monitor the Sun and the Earth's magnetic field.
Teledesic, the company partially owned by Bill Gates that plans to create a giant network of communications satellites, is reported looking at using converted Russian ICBMs to launch some of its satellites.
www.seds.org /spaceviews/970215/tech.html   (648 words)

  
 LUNAR LIBRATION   (Site not responding. Last check: 2007-10-12)
These libration plots indicate the phases of the Moon on it since its starting date is on the first of the Month, not on the beginning of Moon's lunation period.
What it also tells you is that if the plot is located on the far west side, as it is on March 21, the western limb of the Moon is turned toward the Earth, giving the observer a good view of features on that limb.
This is the normal reason lunar observers will use libration plots and it's not generally used for the study of Lunar Transient Phenomena.
www.ltpresearch.org /lunar_libration.htm   (230 words)

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