A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PAIR ANNIHILATION      (PairAnnihilation)
				ELECTRONS , GAMMA RAYS , POSITRONS
PAIR PRODUCTION      (PairProduction)
		PARTICLE PRODUCTION		ELECTRONS , GAMMA RAYS , POSITRONS
PALEOMAGNETISM      (Paleomagnetism)
				CONTINENTAL DRIFT , GEOMAGNETISM , MAGNETIC FIELDS
PARABOLIC ANTENNAS      (ParabolicAntennas)
		ANTENNAS , DIRECTIONAL ANTENNAS		CASSEGRAIN FOCUS
PARABOLIC MIRRORS      (ParabolicMirrors)
				PARABOLIC REFLECTORS
See PARABOLIC REFLECTORS.
PARABOLIC ORBITS      (ParabolicOrbits)
		ORBITS		CIRCULAR ORBITS , COMETS , ELLIPTICAL ORBITS , HYPERBOLIC ORBITS
PARABOLIC REFLECTORS      (ParabolicReflectors)
				DISH ANTENNAS , PARABOLIC MIRRORS , RADAR TELESCOPES , RADIO TELESCOPES , REFLECTING TELESCOPES
PARABOLIC VELOCITY      (ParabolicVelocity)
		VELOCITY		ESCAPE VELOCITY , ORBITS
PARAHYDROGEN      (Parahydrogen)
		MOLECULAR HYDROGEN		ORTHOHYDROGEN
PARALLAXES      (Parallaxes)
			ANNUAL PARALLAX , DIURNAL PARALLAX , DYNAMICAL PARALLAX , KINEMATIC PARALLAX , MOVING CLUSTER PARALLAX , PHOTOMETRIC PARALLAX , SECULAR PARALLAX , STATISTICAL PARALLAX , TRIGONOMETRIC PARALLAX	ASTROMETRY , ASTRONOMICAL UNIT , DISTANCE , DISTANCE MODULUS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PARAMETRIC AMPLIFIERS      (ParametricAmplifiers)
		AMPLIFIERS
PARSEC      (Parsec)
	parallax second			ASTRONOMICAL UNIT , DISTANCE , DISTANCE SCALE , LIGHT YEAR
PARTIAL ECLIPSE      (PartialEclipse)
		ECLIPSES		ECLIPSING BINARY STARS , TOTAL ECLIPSES
PARTICLE ACCELERATION      (ParticleAcceleration)
				ELEMENTARY PARTICLES
PARTICLE ACCRETION      (ParticleAccretion)
				ACCRETION
PARTICLE BEAMS      (ParticleBeams)
				HIGH ENERGY ASTROPHYSICS
PARTICLE CREATION      (ParticleCreation)
				ELEMENTARY PARTICLES
PARTICLE ESCAPE      (ParticleEscape)
				ELEMENTARY PARTICLES
PARTICLE INTERACTIONS      (ParticleInteractions)
				ELEMENTARY PARTICLES
PARTICLE PRODUCTION      (ParticleProduction)
			PAIR PRODUCTION	ELEMENTARY PARTICLES
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PARTICLE PROPAGATION      (ParticlePropagation)
PARTICLES      (Particles)
			ALPHA PARTICLES , BOSONS , ELECTRONS , ELEMENTARY PARTICLES , FUNDAMENTAL PARTICLES , IONS , LEPTONS , NEUTRINOS , PARTONS , PLASMAS , POSITRONS , PROTONS , RELATIVISTIC PARTICLES
Only the broad classes are shown below. Specific types will be found under these, or from the Hierarchical List.
PARTONS      (Partons)
		ELEMENTARY PARTICLES , PARTICLES
PASCHEN BACK EFFECT      (PaschenBackEffect)
				MAGNETIC FIELDS , ZEEMAN SPLITTING
PASCHEN SERIES      (PaschenSeries)
	paschen lines			BALMER SERIES , BRACKETT SERIES , HYDROGEN SPECTRUM , LYMAN SERIES , PFUND SERIES
PAST LIGHT CONE      (PastLightCone)
		LIGHT CONE		FUTURE LIGHT CONE
PAUL TRAP      (PaulTrap)
				ELECTRIC FIELDS , IONS , RADIO FREQUENCIES
P BRANCH      (PBranch)
		MOLECULAR SPECTRA
P CYGNI LINE PROFILES      (PCygniLineProfiles)
		LINE PROFILES		EMISSION LINE STARS , MASS LOSS , S DORADUS STARS , SHELL STARS , SYMBIOTIC STARS
PECULIAR GALAXIES      (PeculiarGalaxies)
		GALAXIES , PECULIAR OBJECTS	COMPACT GALAXIES , DWARF GALAXIES , EMISSION LINE GALAXIES , Ep GALAXIES , INTERACTING GALAXIES , RING GALAXIES , SEYFERT GALAXIES	MARKARIAN GALAXIES
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PECULIAR GIANT STARS      (PeculiarGiantStars)
		GIANT STARS , PECULIAR STARS
PECULIAR MOTIONS      (PeculiarMotions)
				LOCAL STANDARD OF REST , PECULIAR VELOCITY , PROPER MOTIONS , RADIAL VELOCITY , STELLAR MOTIONS
PECULIAR OBJECTS      (PeculiarObjects)
			PECULIAR GALAXIES , PECULIAR STARS
Combine with other terms
PECULIAR STARS      (PeculiarStars)
		PECULIAR OBJECTS	Ap STARS , Bp STARS , HEAVY METAL STARS , HOLMIUM STARS , MAGNETIC STARS , PECULIAR GIANT STARS , PECULIAR VARIABLE STARS	ABNORMAL SPECTRA , ABUNDANCE , CHEMICAL COMPOSITION , EMISSION LINE STARS
Only the broad classes are shown below. Specific types will be found under these, or from the Hierarchical List.
PECULIAR VARIABLE STARS      (PeculiarVariableStars)
		PECULIAR STARS , VARIABLE STARS
PECULIAR VELOCITY      (PeculiarVelocity)
		VELOCITY		LOCAL STANDARD OF REST , PECULIAR MOTIONS , RADIAL VELOCITY , STELLAR MOTIONS
PENCIL BEAMS      (PencilBeams)
				MILLS CROSS ANTENNAS , RADIO INTERFEROMETERS
PENDULUMS      (Pendulums)
		TIMING EQUIPMENT		GEODESY , GRAVITY , OSCILLATIONS
PENROSE PROCESS      (PenroseProcess)
				BLACK HOLES
PENUMBRA      (Penumbra)
				ECLIPSES , LUNAR ECLIPSE , PENUMBRAL FILAMENTS , SOLAR ECLIPSE , SUNSPOTS , UMBRA , WILSON EFFECT
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PENUMBRAL FILAMENTS      (PenumbralFilaments)
				PENUMBRA
PERIAPSIS      (Periapsis)
				PERIASTRON , PERIHELION
PERIASTRON      (Periastron)
		APSIDES		APASTRON , PERIAPSIS
PERICENTER      (Pericenter)
				CENTER OF MASS
PERIGEE      (Perigee)
		APSIDES		APOGEE , EARTH , MOON
PERIHELION      (Perihelion)
		APSIDES		APHELION , EARTH ORBIT , PERIAPSIS , PLANETS
PERIOD      (Period)
		ORBITAL ELEMENTS , PHOTOMETRIC ELEMENTS		BINARY STARS , CYCLE , LIGHT CURVES , ORBITS , PHASE [WAVE] , PLANETS , PULSATING VARIABLE STARS , PULSATION MODES , ROTATION , VARIABLE STARS , VELOCITY CURVES
PERIOD AGE RELATION      (PeriodAgeRelation)
				CEPHEIDS , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION
PERIOD CHANGE      (PeriodChange)
	period variation			BINARY STARS , PULSATING VARIABLE STARS
PERIOD COLOR RELATION      (PeriodColorRelation)
				CEPHEIDS , PERIOD AGE RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PERIOD DENSITY RELATION      (PeriodDensityRelation)
				PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIOD DETERMINATION      (PeriodDetermination)
				BINARY STARS , VARIABLE STARS , WAVEFORM ANALYSIS
PERIODIC COMETS      (PeriodicComets)
		COMETS
PERIODIC ORBITS      (PeriodicOrbits)
		ORBITS	ELLIPTICAL ORBITS
PERIOD LUMINOSITY COLOR RELATION      (PeriodLuminosityColorRelation)
	plc relation			CEPHEIDS , PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIOD LUMINOSITY RELATION      (PeriodLuminosityRelation)
	pl relation			CEPHEIDS , PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIOD MASS RELATION      (PeriodMassRelation)
				PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIOD RADIUS RELATION      (PeriodRadiusRelation)
				CEPHEIDS , PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD SPECTRUM RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIOD SPECTRUM RELATION      (PeriodSpectrumRelation)
				CEPHEIDS , PERIOD AGE RELATION , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PULSATING VARIABLE STARS , RADIUS LUMINOSITY RELATION
PERIPHERALS      (Peripherals)
				COMPUTERS , INSTRUMENTATION
Combine with other terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PERTURBATION      (Perturbation)
				CELESTIAL MECHANICS , N BODY PROBLEM , ORBITS , OSCULATORY ELEMENTS , PERTURBATION THEORY , THREE BODY PROBLEM
PERTURBATION THEORY      (PerturbationTheory)
				CELESTIAL MECHANICS , GRAVITATION , ORBITS , PERTURBATION
PETROLOGY      (Petrology)
		GEOLOGY		PLANETS , SURFACES [CELESTIAL BODIES]
PFUND SERIES      (PfundSeries)
		INFRARED RADIATION		BALMER SERIES , BRACKETT SERIES , HYDROGEN SPECTRUM , LYMAN SERIES , PASCHEN SERIES
PHASE ANGLE      (PhaseAngle)
				MOON , PHASE [MOON] , PLANETS
PHASED ARRAYS      (PhasedArrays)
		ARRAYS		PHASE [WAVE] , RADIO INTERFEROMETERS
PHASE DEFECT      (PhaseDefect)
				MOON , OBLIQUITY OF ECLIPTIC , PHASE [MOON]
PHASE DIFFERENCE      (PhaseDifference)
				PHASE [WAVE]
PHASE EFFECTS      (PhaseEffects)
				PHASE [MOON]
PHASE ERRORS      (PhaseErrors)
				PHASE [WAVE]
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHASE FUNCTION      (PhaseFunction)
				PHASE [WAVE] , RADIATION SCATTERING
PHASE [MOON]      (PhaseMoon)
	lunar phases			ILLUMINATION , METONIC CYCLE , PHASE ANGLE , PHASE DEFECT , PHASE EFFECTS , SAROS CYCLE , TERMINATOR LINES
Of the moon.
PHASE ROTATOR      (PhaseRotator)
				PHASE [WAVE] , RADIO TELESCOPES
PHASE SENSITIVE DETECTORS      (PhaseSensitiveDetectors)
				PHASE SWITCHING INTERFEROMETERS , PHASE [WAVE] , RECEIVERS
PHASE SHIFT      (PhaseShift)
				LIGHT CURVES , PHASE [WAVE] , VARIABLE STARS , VELOCITY CURVES
PHASE SPACE      (PhaseSpace)
				PHASE [WAVE] , VELOCITY SPACE
PHASE SWITCHING      (PhaseSwitching)
				PHASE [WAVE] , RADIO TELESCOPES , RECEIVERS
PHASE SWITCHING INTERFEROMETERS      (PhaseSwitchingInterferometers)
		INTERFEROMETERS		PHASE SENSITIVE DETECTORS , PHASE [WAVE]
PHASE [WAVE]      (PhaseWave)
				BINARY STARS , LIGHT CURVES , PERIOD , PHASE DIFFERENCE , PHASE ERRORS , PHASE FUNCTION , PHASE ROTATOR , PHASE SENSITIVE DETECTORS , PHASE SHIFT , PHASE SPACE , PHASE SWITCHING , PHASE SWITCHING INTERFEROMETERS , PHASED ARRAYS , VARIABLE STARS , VELOCITY CURVES
Of a repeating wave.
PHILLIPS BANDS      (PhillipsBands)
		INFRARED RADIATION , MOLECULAR BANDS , MOLECULAR SPECTRA
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHOSPHORESCENCE      (Phosphorescence)
				IMAGE TUBES , PHOSPHORESCENT SCINTILLATION , SCINTILLATION COUNTERS
PHOSPHORESCENT SCINTILLATION      (PhosphorescentScintillation)
		SCINTILLATION		COSMIC RAY SHOWERS , IMAGE TUBES , PHOSPHORESCENCE , SCINTILLATION COUNTERS
PHOTOCATHODES      (Photocathodes)
		CATHODES , ELECTRODES		IMAGE TUBES , PHOTOMULTIPLIER TUBES
PHOTOCHEMISTRY      (Photochemistry)
				PHOTOGRAPHIC DEVELOPERS , PHOTOGRAPHIC MATERIALS , PHOTOGRAPHIC PROCESSING
PHOTOCONDUCTIVE CELLS      (PhotoconductiveCells)
				PHOTOMULTIPLIER TUBES
PHOTODIODES      (Photodiodes)
		PHOTOELECTRONIC DEVICES	AVALANCHE PHOTODIODES	PHOTOMETRY
PHOTODISSOCIATION      (Photodissociation)
				ABSORPTION
PHOTOELECTRIC INSTRUMENTS      (PhotoelectricInstruments)
			IMAGE TUBES , PHOTOMULTIPLIER TUBES
PHOTOELECTRIC MAGNITUDES      (PhotoelectricMagnitudes)
		APPARENT MAGNITUDES		PHOTOGRAPHIC MAGNITUDES , PHOTOVISUAL MAGNITUDES
PHOTOELECTRIC PHOTOMETERS      (PhotoelectricPhotometers)
		PHOTOMETERS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHOTOELECTRIC PHOTOMETRY      (PhotoelectricPhotometry)
		PHOTOMETRY	BROAD BAND PHOTOMETRY , MEDIUM BAND PHOTOMETRY , NARROW BAND PHOTOMETRY	CCD PHOTOMETRY , PHOTOGRAPHIC PHOTOMETRY
PHOTOELECTRONIC DEVICES      (PhotoelectronicDevices)
			AVALANCHE PHOTODIODES , CHARGE COUPLED DEVICES , CHARGE INJECTION DEVICES , CHARGE TRANSFER DEVICES , IMAGE TUBES , PHOTODIODES , PHOTOMULTIPLIER TUBES , TELEVISION DETECTORS
PHOTOGRAMMETRY      (Photogrammetry)
				MAPS , PHOTOGRAPHS , PHOTOGRAPHY
PHOTOGRAPHIC ASTROMETRY      (PhotographicAstrometry)
		ASTROMETRY		PROPER MOTIONS
PHOTOGRAPHIC DEVELOPERS      (PhotographicDevelopers)
				PHOTOCHEMISTRY , PHOTOGRAPHIC PROCESSING , PHOTOGRAPHS
PHOTOGRAPHIC EMULSIONS      (PhotographicEmulsions)
		DETECTORS , PHOTOGRAPHIC MATERIALS		HALATION , PHOTOGRAPHIC FILMS , PHOTOGRAPHIC PLATES , PHOTOGRAPHS , PHOTOGRAPHY , QUANTUM EFFICIENCY , TURBIDITY
PHOTOGRAPHIC FILMS      (PhotographicFilms)
	films [photographic]	PHOTOGRAPHIC MATERIALS		PHOTOGRAPHIC EMULSIONS , PHOTOGRAPHS , PHOTOGRAPHY
PHOTOGRAPHIC FILTERS      (PhotographicFilters)
		OPTICAL FILTERS
PHOTOGRAPHIC INSTRUMENTS      (PhotographicInstruments)
			CAMERAS , SCHMIDT CAMERAS , SCHMIDT TELESCOPES
PHOTOGRAPHIC MAGNITUDES      (PhotographicMagnitudes)
		APPARENT MAGNITUDES		PHOTOELECTRIC MAGNITUDES , PHOTOVISUAL MAGNITUDES
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHOTOGRAPHIC MATERIALS      (PhotographicMaterials)
			PHOTOGRAPHIC EMULSIONS , PHOTOGRAPHIC FILMS , PHOTOGRAPHIC PLATES	PHOTOCHEMISTRY , PHOTOGRAPHS
PHOTOGRAPHIC PHOTOMETRY      (PhotographicPhotometry)
		PHOTOMETRY	BROAD BAND PHOTOMETRY	CCD PHOTOMETRY , PHOTOELECTRIC PHOTOMETRY
PHOTOGRAPHIC PLATES      (PhotographicPlates)
		PHOTOGRAPHIC MATERIALS		PHOTOGRAPHIC EMULSIONS , PHOTOGRAPHS , PHOTOGRAPHY , RESEAUX
PHOTOGRAPHIC PROCESSING      (PhotographicProcessing)
				DARKROOMS , PHOTOCHEMISTRY , PHOTOGRAPHIC DEVELOPERS , PHOTOGRAPHY , UNSHARP MASKING
PHOTOGRAPHS      (Photographs)
		IMAGES		CAMERAS , MICRODENSITOMETERS , PHOTOGRAMMETRY , PHOTOGRAPHIC DEVELOPERS , PHOTOGRAPHIC EMULSIONS , PHOTOGRAPHIC FILMS , PHOTOGRAPHIC MATERIALS , PHOTOGRAPHIC PLATES
PHOTOGRAPHY      (Photography)
	astrophotography		ALL SKY PHOTOGRAPHY , COLOR PHOTOGRAPHY , FALSE COLOR PHOTOGRAPHY , STREAK PHOTOGRAPHY , ULTRAVIOLET PHOTOGRAPHY	ASTRONOMICAL TECHNIQUES , CAMERAS , DARKROOMS , EDGE EFFECTS , HD CURVE , IMAGES , MICROPHOTOMETERS , OBSERVING TECHNIQUES , PHOTOGRAMMETRY , PHOTOGRAPHIC EMULSIONS , PHOTOGRAPHIC FILMS , PHOTOGRAPHIC PLATES , PHOTOGRAPHIC PROCESSING , SPECTROGRAPHY , UNSHARP MASKING
PHOTOHELIOGRAPHS      (Photoheliographs)
				SPECTROHELIOGRAPHS
PHOTOIONIZATION      (Photoionization)
		IONIZATION		ABSORPTION , AURORAS , ELECTRONS , RECOMBINATION
PHOTOLUMINESCENCE      (Photoluminescence)
		LIGHT EMISSION	X RAY FLUORESCENCE	FLUORESCENCE
PHOTOMETERS      (Photometers)
		OPTICAL INSTRUMENTS , TELESCOPE INSTRUMENTATION	HIGH SPEED PHOTOMETERS , PHOTOELECTRIC PHOTOMETERS , SPECTROPHOTOMETERS	BOLOMETERS , CCD DETECTORS , INFRARED DETECTORS , PHOTOMETRY , PHOTOMULTIPLIER TUBES , POLARIMETERS , RADIOMETERS , ULTRAVIOLET DETECTORS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHOTOMETRIC ELEMENTS      (PhotometricElements)
			LIGHT CURVES , MAXIMA , MINIMA , PERIOD	ECLIPSING BINARY STARS
PHOTOMETRIC PARALLAX      (PhotometricParallax)
		PARALLAXES		PHOTOMETRY
PHOTOMETRIC STANDARD STARS      (PhotometricStandardStars)
		STANDARD STARS		PHOTOMETRY , STANDARD CANDLES
PHOTOMETRIC SYSTEMS      (PhotometricSystems)
			CAPE PHOTOMETRY , DDO PHOTOMETRY , GENEVA PHOTOMETRY , JOHNSON PHOTOMETRY , STROMGREN PHOTOMETRY , WALRAVEN PHOTOMETRY	APPARENT MAGNITUDES , PHOTOMETRY
PHOTOMETRY      (Photometry)
	filter photometry , multicolor photometry	ASTRONOMICAL TECHNIQUES , OBSERVING TECHNIQUES	CCD PHOTOMETRY , INFRARED PHOTOMETRY , PHOTOELECTRIC PHOTOMETRY , PHOTOGRAPHIC PHOTOMETRY , SURFACE PHOTOMETRY , ULTRAVIOLET PHOTOMETRY	APPARENT MAGNITUDES , AUTOMATIC PATROL TELESCOPES , AVALANCHE PHOTODIODES , COLOR , COLOR EQUATION , COLOR EXCESSES , COLOR INDICES , COLOR LUMINOSITY RELATION , COLOR MAGNITUDE RELATION , DRIFT SCANS , E REGIONS , EFFECTIVE TEMPERATURE , F REGIONS , INTERFERENCE FILTERS , INTRINSIC COLORS , MAGNITUDES , OPTICAL FILTERS , PHOTODIODES , PHOTOMETERS , PHOTOMETRIC PARALLAX , PHOTOMETRIC STANDARD STARS , PHOTOMETRIC SYSTEMS , POLARIMETRY , PURKINJE EFFECT , SPECTROPHOTOMETRY , STANDARD CANDLES , TWO COLOR DIAGRAMS
Only the broad classes are shown below. Specific types will be found under these, or from the Hierarchical List.
PHOTOMULTIPLIER TUBES      (PhotomultiplierTubes)
	cells , photocells , photoelectric cells	DETECTORS , PHOTOELECTRIC INSTRUMENTS , PHOTOELECTRONIC DEVICES		AMPLIFIERS , CATHODES , ELECTRODES , INSTRUMENTATION , PHOTOCATHODES , PHOTOCONDUCTIVE CELLS , PHOTOMETERS , QUADRANT DETECTORS , QUANTUM EFFICIENCY , SCINTILLATION COUNTERS
PHOTON COUNTING SYSTEMS      (PhotonCountingSystems)
				COUNTERS
PHOTONS      (Photons)
		BOSONS , ELEMENTARY PARTICLES		ELECTROMAGNETIC WAVES , INVERSE COMPTON EFFECT , INVERSE COMPTON SCATTERING , MESONS , QUANTUM , RADIATION , RADIATION PRESSURE , RADIATIVE RECOMBINATION
PHOTOSPHERE      (Photosphere)
	reversing layer			CHROMOSPHERE , CONTINUUM RADIATION , FACULAE , GRANULATION , GRANULES , SOLAR SURFACE , SUN , SURFACE BRIGHTNESS , SURFACES [CELESTIAL BODIES]
PHOTOVISUAL MAGNITUDES      (PhotovisualMagnitudes)
		APPARENT MAGNITUDES		PHOTOELECTRIC MAGNITUDES , PHOTOGRAPHIC MAGNITUDES , V MAGNITUDE , VISUAL MAGNITUDE
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PHOTOVOLTAIC CELLS      (PhotovoltaicCells)
		SEMICONDUCTOR DEVICES
PIONS      (Pions)
		BOSONS , ELEMENTARY PARTICLES
PITCH ANGLE      (PitchAngle)
				GALACTIC STRUCTURE , SPIRAL ARMS , SPIRAL GALAXIES
PIXEL      (Pixel)
	picture element			DETECTORS , RESOLUTION , TWO DIMENSIONAL DETECTORS
PLAGES      (Plages)
	flocculi , solar plages			CHROMOSPHERE , FACULAE , SUNSPOTS
PLANCK BLACK BODY FORMULA      (PlanckBlackBodyFormula)
				PLANCK CONSTANT , RADIATION
PLANCK CONSTANT      (PlanckConstant)
				PLANCK BLACK BODY FORMULA
PLANE POLARIZATION      (PlanePolarization)
		POLARIZATION [WAVES]		CIRCULAR POLARIZATION
PLANETARIA      (Planetaria)
				MOTION , OBSERVATORIES , ORRERIES
PLANETARY      (Planetary)
See SN for PLANETS.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PLANETARY NEBULAE      (PlanetaryNebulae)
		EMISSION NEBULAE , EVOLVED STARS , NEBULAE		ANSAE , CENTRAL STARS , EMISSION LINE STARS , EXCITING STARS , HARMAN SEATON SEQUENCE , MASS LOSS , RING NEBULAE
PLANETARY RINGS      (PlanetaryRings)
		RINGS		PLANETS , RESONANCE GAPS , RING DIVISIONS , ROCHE LIMIT , SHEPHERD SATELLITES
PLANETARY SYSTEMS      (PlanetarySystems)
			SOLAR SYSTEM
PLANETARY THEORY      (PlanetaryTheory)
				CELESTIAL MECHANICS , SOLAR SYSTEM
PLANETESIMALS      (Planetesimals)
				MINOR PLANETS , PLANETS , PROTOPLANETS , SATELLITES , SOLAR SYSTEM
PLANETOLOGY      (Planetology)
				GEOLOGY
PLANETS      (Planets)
			EARTH , EXTRASOLAR PLANETS , GIANT PLANETS , HYPOTHETICAL PLANETS , INNER PLANETS , OUTER PLANETS	AERONOMY , ALIGNMENT [PLANETS] , APHELION , ASTROLOGY , ATMOSPHERES , BODES LAW , BOUNDARY LAYERS , CENTER OF MASS , COLLISIONS , COMPOSITION , CORES , CRATERS , CRUST , DUST STORMS , EQUATORIAL BULGE , EVOLUTION , EXOSPHERE , GALILEAN SATELLITES , GEOLOGY , GEOMAGNETISM , GREENHOUSE EFFECT , INTERIORS , LITHOSPHERES , MANTLES , MAPS , MEAN EQUINOX , OBLATENESS , OCCULTATIONS , ORBIT DETERMINATION , ORBITS , ORIGIN , PERIHELION , PERIOD , PETROLOGY , PHASE ANGLE , PLANETARY RINGS , PLANETESIMALS , POLAR CAPS , POLAR REGIONS , PROTOPLANETS , RESONANCE GAPS , RILLES , RING DIVISIONS , ROCHE LIMIT , SATELLITES , SEMIMAJOR AXIS , SOLAR NEBULA , SOLAR PLANETARY RELATIONS , SOLAR SYSTEM , SPACE EXPLORATION , STRUCTURE , SURFACES [CELESTIAL BODIES] , SYNODIC PERIOD , SYZYGY , TOPOGRAPHY , TWO BODY PROBLEM , VOLATILES , VOLCANOES , WATER ICE , WATER VAPOR
Combine either PLANET or PLANETARY with other terms.
PLANET SATELLITES      (PlanetSatellites)
		SATELLITES
PLASMA CLOUDS      (PlasmaClouds)
		CLOUDS		IONS , PLASMA JETS , PLASMAS
PLASMA JETS      (PlasmaJets)
		JETS		IONS , PLASMA CLOUDS , PLASMA LOOPS , PLASMAS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PLASMA LOOPS      (PlasmaLoops)
				PLASMA JETS , PLASMAS
PLASMAPAUSE      (Plasmapause)
				PLASMAS
PLASMA PHYSICS      (PlasmaPhysics)
				MAGNETOHYDRODYNAMICS , PLASMAS
PLASMAS      (Plasmas)
	cosmic plasmas	PARTICLES	COLLISIONAL PLASMAS , LOW TEMPERATURE PLASMAS , RELATIVISTIC PLASMAS , SOLAR WIND , STELLAR WINDS	ELEMENTARY PARTICLES , ENERGETIC PARTICLES , H II REGIONS , HOLTSMARK APPROXIMATION , IONIZED GASES , IONS , PLASMA CLOUDS , PLASMA JETS , PLASMA LOOPS , PLASMA PHYSICS , PLASMA WAVES , PLASMAPAUSE , RADIATION BELTS , RADIATIVE RECOMBINATION , THERMODYNAMICS , VISCOSITY
PLASMA WAVES      (PlasmaWaves)
				ION PLASMA WAVES , MAGNETOHYDRODYNAMICS , PLASMAS
P MAGNITUDE      (PMagnitude)
		APPARENT MAGNITUDES		FAR INFRARED RADIATION , INFRARED PHOTOMETRY
POGSON SCALE      (PogsonScale)
				MAGNITUDES
POINCARE THEOREM      (PoincareTheorem)
				STAR CLUSTERS , STELLAR DYNAMICS
POINTING ACCURACY      (PointingAccuracy)
				CONTROL SYSTEMS , POINTING ERRORS , TELESCOPES , TRACKING
POINTING ERRORS      (PointingErrors)
				CONTROL SYSTEMS , POINTING ACCURACY , TELESCOPES , TRACKING
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
POINT SPREAD FUNCTION      (PointSpreadFunction)
				ATMOSPHERIC REFRACTION , SEEING , TURBULENCE [EARTH ATMOSPHERE]
POLAR AXIS      (PolarAxis)
				CELESTIAL POLES , TELESCOPE MOUNTINGS
POLAR CAPS      (PolarCaps)
				EARTH , PLANETS
POLAR DIAGRAM      (PolarDiagram)
				ANTENNA DESIGN , BEAMWIDTH , RADIO ANTENNAS , SENSITIVITY , SIDELOBES
POLARIMETERS      (Polarimeters)
		OPTICAL INSTRUMENTS , TELESCOPE INSTRUMENTATION		PHOTOMETERS , POLARIMETRY
POLARIMETRY      (Polarimetry)
		ASTRONOMICAL TECHNIQUES , OBSERVING TECHNIQUES		PHOTOMETRY , POLARIMETERS , POLARIZATION [WAVES]
POLARIZATION [CHARGE SEPARATION]      (PolarizationChargeSeparation)
		MAGNETO OPTICAL EFFECTS		ANISOTROPY , IONS
POLARIZATION [WAVES]      (PolarizationWaves)
	light polarization		CIRCULAR POLARIZATION , PLANE POLARIZATION , X RAY POLARIZATION	ELECTROMAGNETIC WAVES , FARADAY EFFECT , OPTICAL PROPERTIES , POLARIMETRY , POLARIZED LIGHT , POLARIZED RADIATION , RADIATION SCATTERING , STOKES PARAMETERS
POLARIZED LIGHT      (PolarizedLight)
		LIGHT		POLARIZATION [WAVES]
POLARIZED RADIATION      (PolarizedRadiation)
		RADIATION		FARADAY EFFECT , POLARIZATION [WAVES] , STOKES PARAMETERS , X RAY POLARIZATION
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
POLAR MOTION      (PolarMotion)
		MOTION		CHANDLER WOBBLE , EARTH ROTATION , LATITUDE VARIATION , NUTATION , PRECESSION
POLAR ORBITS      (PolarOrbits)
		ORBITS		ARTIFICIAL SATELLITES
POLAR REGIONS      (PolarRegions)
				PLANETS
POLAR TIDES      (PolarTides)
		TIDES
POLES      (Poles)
			CELESTIAL POLES , ECLIPTIC POLES , GALACTIC POLES , NADIR , ZENITH
POLISHING      (Polishing)
			FIGURING	LENSES , MIRRORS , SURFACES [OPTICAL]
POLLUTION      (Pollution)
			AIR POLLUTION , LIGHT POLLUTION , SPACE POLLUTION	GREENHOUSE EFFECT , SITE TESTING
POLYCYCLIC HYDROCARBON      (PolycyclicHydrocarbon)
		HYDROCARBONS
POLYTROPES      (Polytropes)
				MODELS , STELLAR STRUCTURE
POPULATION II CEPHEIDS      (PopulationIiCepheids)
		POPULATION II STARS	RR LYRAE STARS , W VIRGINIS STARS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
POPULATION II STARS      (PopulationIiStars)
		OLD STARS	DISK POPULATION , DISK STARS , HALO STARS , HORIZONTAL BRANCH STARS , POPULATION II CEPHEIDS , SX PHOENICIS STARS	GALACTIC HALO , GALACTIC NUCLEI , GLOBULAR STAR CLUSTERS , INTERMEDIATE POPULATION STARS , STELLAR POPULATIONS , SUBLUMINOUS STARS
POPULATION INVERSION      (PopulationInversion)
				ATOMIC PROCESSES , LASERS , MASERS , STIMULATED EMISSION
POPULATION I STARS      (PopulationIStars)
	extreme population I stars		YOUNG STARS	OPEN STAR CLUSTERS , SPIRAL ARMS , STELLAR POPULATIONS , YOUNG STAR CLUSTERS
POSITION ANGLE      (PositionAngle)
		ORBITAL ELEMENTS		BINARY STARS , ORBITS , ORIENTATION
POSITIONS      (Positions)
			APPARENT POSITIONS , TRUE POSITIONS	COORDINATE SYSTEMS , FUNDAMENTAL SYSTEM , REFERENCE SYSTEMS , SPHERICAL COORDINATES , STANDARD STARS
Combine with other terms
POSITRONS      (Positrons)
		ANTIPARTICLES , LEPTONS , NUCLEAR RADIATION , PARTICLES		ELECTRONS , PAIR ANNIHILATION , PAIR PRODUCTION , RADIOACTIVITY
POSTMAINSEQUENCE STARS      (PostmainsequenceStars)
		EVOLVED STARS , NONMAINSEQUENCE STARS	GIANT STARS , SUBGIANT STARS , SUPERGIANT STARS
Only the broad classes are shown below. Specific types will be found under these, or from the Hierarchical List. Excluding advanced evolution.
POTENTIAL ENERGY      (PotentialEnergy)
		ENERGY		KINETIC ENERGY
POTENTIAL THEORY      (PotentialTheory)
In mathematics.
POWER      (Power)
Combine with other terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
POYNTING ROBERTSON EFFECT      (PoyntingRobertsonEffect)
				RADIATION PRESSURE , SOLAR WIND , STELLAR WINDS
p PROCESS      (pProcess)
				NUCLEOSYNTHESIS , r PROCESS , s PROCESS , SUPERNOVAS
PREAMPLIFIERS      (Preamplifiers)
		AMPLIFIERS
PRECESSION      (Precession)
				ASTROMETRY , CELESTIAL MECHANICS , EARTH ROTATION , EQUATION OF THE EQUINOXES , NUTATION , OBLIQUITY OF ECLIPTIC , POLAR MOTION
PRECISION      (Precision)
				LIMITING MAGNITUDES , SENSITIVITY
Combine with other terms
PRECURSOR PULSE      (PrecursorPulse)
				PULSARS
PREDICTIONS      (Predictions)
				FORECASTS
Combine with other terms
PREGALACTIC STARS      (PregalacticStars)
		OLD STARS
PREMAINSEQUENCE STARS      (PremainsequenceStars)
	early stage stars	NONMAINSEQUENCE STARS , YOUNG STARS	FLASH STARS , HERBIG HARO OBJECTS , PROTOSTARS , RW AURIGAE STARS , T TAURI STARS	ORION POPULATION STARS , STAR FORMATION , T ASSOCIATIONS
PRESOLAR NEBULA      (PresolarNebula)
				SOLAR SYSTEM
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PRESSURE      (Pressure)
				RADIATION PRESSURE , RANKINE HUGONIOT RELATIONS , VACUUM
Combine with other terms
PRESSURE BROADENING      (PressureBroadening)
		LINE BROADENING		DOPPLER BROADENING , LINE SPECTRA , NATURAL LINE WIDTH , SPECTROSCOPY , ZEEMAN SPLITTING
PRIMARY LENSES      (PrimaryLenses)
		LENSES , OBJECTIVES		REFRACTING TELESCOPES
PRIMARY MIRRORS      (PrimaryMirrors)
		MIRRORS , OBJECTIVES , TELESCOPE MIRRORS		REFLECTING TELESCOPES , SECONDARY MIRRORS
PRIME FOCUS      (PrimeFocus)
		FOCUS		CASSEGRAIN FOCUS , COUDE FOCUS , NASMYTH FOCUS
PRIMORDIAL FIREBALL      (PrimordialFireball)
		COSMOLOGY		BIG BANG THEORY
PRIMORDIAL GALAXIES      (PrimordialGalaxies)
		GALAXIES
PRISMS      (Prisms)
			OBJECTIVE PRISMS	GRISMS , OPTICAL INSTRUMENTS , PRISM SPECTROGRAPHS , SPECTRA , SPECTROGRAPHS
PRISM SPECTROGRAPHS      (PrismSpectrographs)
		SPECTROGRAPHS		GRATING SPECTROGRAPHS , PRISMS
PROGENITORS      (Progenitors)
	precursors , prenovas , presupernovas			NOVAS , SUPERNOVAS
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PROMINENCES      (Prominences)
	chromospheric eruptions		ACTIVE PROMINENCES , QUIESCENT PROMINENCES	CHROMOSPHERE , FILAMENTS [SOLAR] , FLARES , HANLE EFFECT , OPTICAL FLARES , SOLAR ACTIVITY , SUN , SUNSPOTS
PROPAGATION      (Propagation)
Combine with other terms
PROPER MOTIONS      (ProperMotions)
		MOTION , SPACE MOTION		GALACTIC ROTATION , KINEMATICS , LOCAL STANDARD OF REST , MOVING CLUSTER PARALLAX , PECULIAR MOTIONS , PHOTOGRAPHIC ASTROMETRY , RADIAL VELOCITY , RADIANT [MOVING CLUSTER] , SECULAR PARALLAX , STELLAR DYNAMICS , STELLAR MOTIONS , TRANSVERSE VELOCITY
PROPERTIES      (Properties)
			MAGNETIC PROPERTIES , MECHANICAL PROPERTIES , OPTICAL PROPERTIES , SURFACE PROPERTIES , THERMAL PROPERTIES
Combine with other terms
PROPORTIONAL COUNTERS      (ProportionalCounters)
		MEASURING INSTRUMENTS		X RAY DETECTORS
PROTOCLUSTERS      (Protoclusters)
		CLUSTERS		CLUSTERS OF GALAXIES , COLLAPSING CLOUDS , COSMOGONY , COSMOLOGY , STAR CLUSTERS
PROTOGALAXIES      (Protogalaxies)
		GALAXIES , GASEOUS SPHERES		COLLAPSING CLOUDS , COSMOGONY , COSMOLOGY
PROTON PROTON REACTION      (ProtonProtonReaction)
	proton proton cycle	HYDROGEN BURNING		CARBON NITROGEN CYCLE , NUCLEAR FUSION , STELLAR INTERIORS
PROTONS      (Protons)
		FUNDAMENTAL PARTICLES , PARTICLES		ALPHA PARTICLES , ANTIPROTONS , NUCLEI [ATOMS]
PROTOPLANETARY NEBULAS      (ProtoplanetaryNebulas)
		COLLAPSING CLOUDS		COSMOGONY , PROTOPLANETS , SOLAR NEBULA
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PROTOPLANETS      (Protoplanets)
				PLANETESIMALS , PLANETS , PROTOPLANETARY NEBULAS , SATELLITES , SOLAR NEBULA , SOLAR SYSTEM
PROTOSTARS      (Protostars)
		GASEOUS SPHERES , PREMAINSEQUENCE STARS		BIRTH RATES , BOK GLOBULES , COLLAPSING CLOUDS , HERBIG HARO OBJECTS , STAR FORMATION , STELLAR EVOLUTION , T TAURI STARS
PULSARS      (Pulsars)
		COLLAPSED STARS , DEGENERATE STARS , EVOLVED STARS , RADIO SOURCES , RELATIVISTIC STARS	BINARY PULSARS , OPTICAL PULSARS , RADIO PULSARS , X RAY PULSARS	FREQUENCY SHIFT , NEUTRON STARS , PRECURSOR PULSE , PULSE DURATION , PULSE ENERGIES , PULSE INTENSITY , PULSE PROFILES , PULSE STRUCTURE , PULSE WIDTH , PULSE WINDOW , RAPID OSCILLATIONS , SUPERNOVA REMNANTS , SUPERNOVAS
PULSATING VARIABLE STARS      (PulsatingVariableStars)
		INTRINSIC VARIABLE STARS , VARIABLE STARS	53 PERSEI STARS , BETA CEPHEI STARS , BL HERCULIS STARS , CEPHEIDS , DELTA DELPHINI STARS , DELTA SCUTI STARS , DOUBLE MODE CEPHEIDS , DOUBLE MODE VARIABLE STARS , DWARF CEPHEIDS , IRREGULAR VARIABLE STARS , LAMBDA ERIDANI STARS , LONG PERIOD VARIABLE STARS , MIRA VARIABLE STARS , MULTIPERIODIC VARIABLE STARS , RR LYRAE STARS , RV TAURI STARS , S VULPECULAE STARS , SEMIREGULAR VARIABLE STARS , SX PHOENICIS STARS , W VIRGINIS STARS , ZZ CETI STARS	ASTEROSEISMOLOGY , DOUBLE MODE PULSATION , HE+ IONIZATION ZONE , KAPPA MECHANISM , MULTIPERIODIC PULSATION , NONRADIAL PULSATIONS , OVERTONE MODES , PERIOD , PERIOD CHANGE , PERIOD COLOR RELATION , PERIOD DENSITY RELATION , PERIOD LUMINOSITY COLOR RELATION , PERIOD LUMINOSITY RELATION , PERIOD MASS RELATION , PERIOD RADIUS RELATION , PERIOD SPECTRUM RELATION , PULSATION MODES , PULSATION THEORY
PULSATION MODES      (PulsationModes)
			FUNDAMENTAL MODE , OVERTONE MODES	MULTIPERIODIC PULSATION , MULTIPERIODIC VARIABLE STARS , NONRADIAL PULSATIONS , PERIOD , PULSATING VARIABLE STARS , PULSATION THEORY , PULSATIONS
PULSATIONS      (Pulsations)
				AMPLITUDES , ASTEROSEISMOLOGY , PULSATION MODES
Combine with other terms
PULSATION THEORY      (PulsationTheory)
				HE+ IONIZATION ZONE , PULSATING VARIABLE STARS , PULSATION MODES
PULSE COUNTERS      (PulseCounters)
				AMPLIFIERS , PULSES
PULSE COUNTING      (PulseCounting)
				AMPLIFIERS , PULSES
PULSE DURATION      (PulseDuration)
				PULSARS , PULSES
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Description	alt	broader	narrower	related
PULSE ENERGIES      (PulseEnergies)
				PULSARS , PULSES
PULSE INTENSITY      (PulseIntensity)
				PULSARS , PULSES
PULSE PROFILES      (PulseProfiles)
				PULSARS , PULSES
PULSES      (Pulses)
				PULSE COUNTERS , PULSE COUNTING , PULSE DURATION , PULSE ENERGIES , PULSE INTENSITY , PULSE PROFILES , PULSE STRUCTURE , PULSE WIDTH , PULSE WINDOW
Combine with other terms
PULSE STRUCTURE      (PulseStructure)
				PULSARS , PULSES
PULSE WIDTH      (PulseWidth)
				PULSARS , PULSES
PULSE WINDOW      (PulseWindow)
				PULSARS , PULSES
PURKINJE EFFECT      (PurkinjeEffect)
				PHOTOMETRY , VARIABLE STARS , VISUAL MAGNITUDE , VISUAL OBSERVATIONS

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Thu Jul 3 15:11:37 2008