Term Index (R)
- R:
- R band: band of visible light around 6500 angstroms
- spectral resolution (R): measure of a spectrograph's ability to resolve features of the spectrum
- R band: band of visible light around 6500 angstroms
- R to the 1/4 law:
- Röntgensatellit:
- ROSAT: 1990s German space x-ray telescope
- r-process: synthesization of elements through neutron capture faster than beta decay
- r0:
- seeing: apparent blurring and twinkling of objects seen through atmosphere
- R200:
- R200c:
- R200m:
- R500:
- R500c:
- Re:
- rL:
- Laplace radius (rL): a radius for a stable orbit of a satellite around a planet
- Rm:
- Reynolds number (Re): measure reflecting a fluid system's propensity to turbulence
- Rsp:
- RA:
- RAC:
- Phoenix: Mars probe launched by NASA in 2007 with lander
- radar: probe based on reflecting radio waves
- radial:
- radial drift barrier:
- radial epicyclic frequency:
- radial mode:
- radial velocity (RV): component of velocity toward or away from observer
- radial velocity method:
- radial velocity observatory:
- radiance: measure of EMR to/from a solid angle through and area
- radiant:
- meteoroid: rocky object in solar system, smaller than an asteroid
- radiant exposure:
- flux: flow rate per unit area
- radiant flux: measure of brightness
- radiated excitation:
- radiation:
- radiation detector:
- radiation era: early universe era when radiation pressure dominated
- radiation flux:
- radiation hydrodynamics (RHD): hydrodynamics plus the affects of EMR
- HARM²: technique for parallelizing computations of radiation with hydrodynamics
- hydrodynamics: study of liquids in motion
- radiation magnetohydrodynamics:
- radiation pattern:
- radiation pressure: the pressure exerted by electromagnetic radiation
- radiation-dominated era:
- radiation era: early universe era when radiation pressure dominated
- radiative cooling timescale:
- timescale (t,τ): general length of time something takes
- radiative flux: power passing through a unit area
- radiative flux density:
- radiative forcing (RF): difference between a planet's incoming and outgoing radiation
- radiative timescale:
- timescale (t,τ): general length of time something takes
- radiative transfer (RT): energy transfer in the form of electromagnetic radiation
- radiative transfer code (RT code): computer model of a gas's radiative transfer
- radiative transfer equation:
- radiative transfer model (RTM): models of radiative transfer, often computerized
- radiative-convective climate model:
- radical:
- hydroxyl (OH): compound of hydrogen and oxygen, one atom each
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- 1 Jansky Empty Field Survey (1 Jy): survey to find optical identifications for weak radio sources
- 1.3mm observation: observation frequency useful for detecting dust
- 3C 273: first quasar discovered
- 3C 295: distant radio galaxy
- 3C 303: Seyfert galaxy
- 3C 327: elliptical radio galaxy
- 3C 48: radio galaxy/quasar
- 3C 9: first quasar discovered
- 87GB Catalog of Radio Sources (87GB): 1980s Green Bank radio survey
- Allen Telescope Array (ATA): array of radio telescopes in northern California for SETI
- antenna pattern: a radio telescope's pattern of directional sensitivity
- Arecibo Observatory (NAIC): large 305m radio telescope in Puerto Rico
- Arecibo Occultation Survey (AO): 1960s radio survey using occultations by the Moon
- ASPECS: millimeter survey of HUDF
- ASTRON: Netherlands radio astronomy research organization
- Atacama Large Millimeter Array (ALMA): large radio telescope array in Chile
- Australia Telescope Compact Array (ATCA): radio telescope in eastern Australia
- Australian Square Kilometre Array Pathfinder (ASKAP): radio telescope array of 36 12m dishes
- back end instrument: instruments of a telescope that process or combine signals
- Badgerys Creek Interferometer 101MHz Survey (Mills): early 1950s survey of southern-hemisphere radio sources
- Becker, White, and Edwards Catalog (BWE): 1990s radio catalog from a 91m Green Bank Telescope survey
- Bologna Survey of Radio Sources: 1970s-1980s radio survey
- Cambridge Catalog of Radio Sources: series of catalogs of northern hemisphere sources
- Canadian Hydrogen Intensity Mapping Experiment (CHIME): radio telescope mapping distant neutral hydrogen
- COMAP: high frequency radio telescope to map CO
- Combined Array for Research in Millimeter-wave Astronomy (CARMA): array of radio telescopes in eastern California
- confusion limit: limit on telescope imaging due to too many sources in the same region
- Cosmic Anisotropy Telescope (CAT): 1990s interferometer to measure CMB variations
- Cosmic Lens All-sky Survey (CLASS): radio survey aimed at gravitational lenses
- CRATES: catalog of 8.4GHz data on radio sources
- Cygnus A (3C 405,QSO B1957+405): early-discovered radio galaxy and quasar
- cylindrical telescope: telescope with cylindrical reflectors
- Dominion Observatory 10.03 MHz Source Catalog (DB): 1960s survey of northern-hemisphere radio sources
- Dominion Observatory 1420 MHz Source Catalog (DA): 1960s survey of northern-hemisphere radio sources
- Dominion Radio Astrophysical Observatory (DRAO): radio observatory in British Columbia, Canada
- downconverter: device that reduces the frequency of a signal
- Dwingeloo Obscured Galaxy Survey (DOGS): radio survey of ZOA for 21cm lines indicating galaxies
- Earth-sized VLBI: ground-based VLBI with near-maximal baseline
- Effelsberg 100-m Radio Telescope: German large single-dish radio telescope
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
- European VLBI Network (EVN): consortium of radio telescopes to coordinate VLBI efforts
- Event Horizon Telescope (EHT): growing VLBI network
- Fanaroff-Riley classification: a classification of the radio characteristics of radio sources
- FAST: Arecibo-like 500m telescope in deployment in China
- Fast Fourier Transform Telescope: proposed all-digital telescope with synthetic aperture
- fast radio burst (FRB): astronomical high energy radio pulses of a few milliseconds
- FIRST: 1990s radio survey
- focal plane array (FPA): array of receivers at the focus of a radio telescope
- Fourth Cambridge Catalog of Radio Sources (4C): 1960s catalog of northern hemisphere 178MHz sources
- frequency modulation (FM): changing the frequency of a signal's carrier
- front end instrument: instruments of a telescope that detect and encode the signal
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
- Gould's Belt Distances Survey (GOBELINS): survey of parallax distances to Gould's Belt YSOs
- Green Bank 140 Foot Telescope: West Virginia radio telescope
- Green Bank 300ft Telescope (GB300): former large radio telescope at Green Bank
- Green Bank 6-cm Radio Source Catalog (GB6): catalog of from 1980s northern-hemisphere radio survey
- Green Bank Telescope (GBT): West Virginia large radio telescope
- Greenland Telescope (GLT): 12m radio telescope in Greenland
- GUPPI: radio-telescope back-end aimed at processing pulsar data
- HERA: low frequency radio telescope
- HIRAX: radio telescope array 21 cm surveying
- Institut de radioastronomie millimétrique (IRAM): organized radio astronomy collaboration between France, Germany, and Spain
- ionosphere: layers of Earth atmosphere with significant ions
- IRAM 30m Telescope: millimeter-range radio telescope in Sierra Nevada, Spain
- jansky (Jy): unit of measurement of spectral flux density
- low frequency radio astronomy: astronomy using the lower end of the radio spectrum
- Low-frequency Array (LOFAR): low frequency radio telescope
- Mark II (MKII): 38m radio telescope in England
- MeerKAT: new radio telescope in South Africa
- microwave: electromagnetic radiation, frequency 300MHz to 300GHz
- millimeter astronomy: observation and analysis at wavelengths on the order of a millimeter
- MOJAVE: program to monitor AGN jet radio brightness and polarization
- multichroic feedhorn array: radio array with sensors for two or more bands
- Murchison Widefield Array (MWA): low frequency radio telescope
- MUSTANG: bolometer array on the Green Bank Telescope
- Nançay Radio Telescope (NRT): France large single-dish radio telescope
- NANTEN2: millimeter telescope in Chile
- National Radio Astronomy Observatory (NRAO): US-operated radio astronomy organization
- Next Generation Very Large Array (ngVLA): planned radio telescope array as a follow-on to ALMA and the Jansky VLA
- Northern Extended Millimeter Array (NOEMA): large radio telescope array under construction in Europe
- NRAO Catalog (NRAO): 1960s followup to Cambridge radio surveys
- Ohio Radio Survey: 1960s radio survey by Ohio State University
- Ooty Radio Telescope (ORT): cylindrical radio telescope in India
- Owens Valley Radio Observatory (OVRO): group of radio telescopes in California near the VLBA
- PAPER: radio interferometer for 21cm measurement
- Parkes Catalog (PKS): catalog of from 1960s-1990 of radio sources in southern hemisphere
- Parkes Observatory: Australian large single-dish radio telescope
- Parkes Pulsar Timing Array (PPTA): organization of pulsar timing observatories
- Parkes-MIT-NRAO Surveys (PMN): 1990 southern-hemisphere radio surveys
- phased array: method of using a set of antennas directionally
- plasma frequency: frequency of electron plasma oscillation
- pulsar timing array (PTA): cooperating set of pulsar timing observatories
- PUPPI: Arecibo radio-telescope instrument aimed at observing pulsars
- radar: probe based on reflecting radio waves
- radio astronomy: astronomy observation and analysis of radio EMR
- radio frequency interference (RFI): transmissions in a frequency band under observation
- radio galaxy (RG): a galaxy emitting a lot of radio
- Radio Galaxy Zoo (RGZ): crowd-sourced classification of radio galaxies
- radio relics: clouds from past galaxy emitting radio synchrotron radiation
- radio source (RS): something in the sky generating radio signal
- radio source counts: using radio source population characteristics to determine curvature
- radio star: star emitting much radio
- radio telescope: telescope that operates in the radio frequency range of EMR
- radiometer equation: shows how long to observe a radio source
- RASS/Green Bank Catalog (RGB,RASSGB): combined list of radio galaxies from Rosat and Green Bank surveys
- RMS astronomy: collective term for radio, millimeter, and submillimeter
- Sardinia Radio Telescope (SRT): Italian large single-dish radio telescope
- Spektr-R: 10m space radio telescope
- Square Kilometre Array (SKA): radio telescope collecting a square kilometer
- Strong Source Surveys: series of 1970s/1980s 5GHz surveys
- Submillimeter Array (SMA): radio interferometer in Hawaii
- submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
- Texas Survey of Radio Sources at 365 MHz (TXS): 1970s/1970s radio survey made with the Texas Interferometer
- Third Cambridge Catalogue of Radio Sources (3C): 1959 catalog of northern hemisphere 159MHz sources
- USS Sources: catalog of sources with steep spectral index
- VERA: VLBI project to map the Milky Way
- Very Large Array (VLA): radio telescope in New Mexico
- Very Long Baseline Array (VLBA): radio interferometer stretching 8000 km
- Very Small Array (VSA): radio interferometer in Canary Islands
- very-long-baseline interferometry (VLBI): interferometry based upon storing timing data at each telescope
- Westerbork Synthesis Radio Telescope (WSRT): radio telescope array of 14 dishes in Netherlands
- Westerhout Radio Survey (W): 1950s radio survey of the galactic plane
- radio astronomy: astronomy observation and analysis of radio EMR
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- radio frequency:
- radio frequency interference (RFI): transmissions in a frequency band under observation
- radio galaxy (RG): a galaxy emitting a lot of radio
- Radio Galaxy Zoo (RGZ): crowd-sourced classification of radio galaxies
- radio interferometry:
- radio millimeter submillimeter wavelength astronomy:
- RMS astronomy: collective term for radio, millimeter, and submillimeter
- radio relics: clouds from past galaxy emitting radio synchrotron radiation
- radio source (RS): something in the sky generating radio signal
- radio source counts: using radio source population characteristics to determine curvature
- radio source star:
- radio star: star emitting much radio
- radio telescope: telescope that operates in the radio frequency range of EMR
- radio waves:
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- radio window:
- atmospheric window: frequency bands in which the atmosphere passes electromagnetic radiation
- radio YSO:
- radio-loud:
- radio-loud blazar:
- radio-loud quasar:
- radio-quiet:
- radioactive dating: determining the age of a substance that has a radioactive component
- radioactive decay: changes in atomic nuclei that happen over time
- radioactive decay timescale:
- radioactive heating: a source of heat of some planets and moons
- radioactive isotope:
- isotope: subclass of an element with a specific number of nucleons
- radioactivity:
- RadioAstron:
- Radioisotope Heat Unit:
- MMRTG: power source for space probes
- radiometer: device for measuring radiant flux
- radiometer equation: shows how long to observe a radio source
- radiometric dating:
- radius:
- radius of stability:
- radius valley:
- Fulton gap: planets with radius 1.5 to 2 Earth radii are rare
- Ralph:
- ram pressure: pressure on a body moving through a fluid
- ram-pressure stripping:
- RAMSES: hydrodynamic simulation system
- random forest: algorithmic method of developing decision trees
- random walk: movement with random turns
- rapid neutron-capture-process:
- r-process: synthesization of elements through neutron capture faster than beta decay
- rapid quenching:
- Rapid Telescopes For Optical Response:
- RAPTOR: automated array of telescopes to uncover and track transients
- rapid weathering:
- weathering: changes in surface due to contact with atmosphere
- RAPTOR: automated array of telescopes to uncover and track transients
- rare earth element:
- lanthanide (Ln): element with atomic numbers 57 through 71
- RASS:
- RASS/Green Bank Catalog (RGB,RASSGB): combined list of radio galaxies from Rosat and Green Bank surveys
- RASSGB:
- ratio:
- ratio of total to selective visual extinction:
- reddening: red appearance of astronomical objects because blue light is attenuated by dust
- ray tracing:
- HARM²: technique for parallelizing computations of radiation with hydrodynamics
- Rayleigh criterion:
- angular resolution: measure of a telescope's ability to distinguish spatial detail
- apodization: improving telescope images by manipulating diffraction
- PSF fitting: untangling airy disks to gain effective resolution
- Rayleigh distribution:
- Rayleigh scattering: wave scattering by particles smaller than the wavelength
- Rayleigh-Taylor instability:
- RBS:
- RC:
- RCT:
- RD:
- dropout: means of identifying distant galaxies
- RDCS:
- ROSAT: 1990s German space x-ray telescope
- RDS:
- ROSAT: 1990s German space x-ray telescope
- Re:
- Reynolds number (Re): measure reflecting a fluid system's propensity to turbulence
- Re-simulated Halo Sample for Statistics Observable-mass Distribution Study:
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- reaction:
- reaction wheel:
- K2: second Kepler mission that worked around failed equipment
- REASON:
- recessional velocity:
- redshift (z): change to longer wavelengths due to Doppler affects
- recombination: time when the universe's ionized hydrogen atoms neutralized
- reconnection sheet:
- current sheet: narrow sheet within a magnetic field where current flows
- RECONS: consortium for research on stars near the Sun
- recurrent nova:
- nova: white dwarf explosion
- red:
- R band: band of visible light around 6500 angstroms
- red and dead:
- red dropout galaxy:
- dropout: means of identifying distant galaxies
- red dwarf: small, cool main-sequence star
- red edge:
- red galaxy:
- red giant: reddish, giant late stage of stellar evolution
- red noise: noise tending toward lower frequencies
- Red Spot:
- red-giant branch (RGB): a stage in the evolution of some smaller stars
- reddening: red appearance of astronomical objects because blue light is attenuated by dust
- extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
- redox:
- redox potential:
- redshift (z): change to longer wavelengths due to Doppler affects
- redshift parameter:
- redshift (z): change to longer wavelengths due to Doppler affects
- redshift space: concept of space using redshift as the radial dimension
- redshift space distortion:
- redshift space: concept of space using redshift as the radial dimension
- redshift survey: survey of the universe aiming at three dimensions
- redshift space: concept of space using redshift as the radial dimension
- redshift-angular size relation: how observed size depends on redshift
- redshift-magnitude relation: how apparent magnitude depends on redshift
- reduced mass: the reciprocal of the sum of the reciprocals of the masses of two objects
- reduced Planck constant:
- reducing agent:
- reducing atmosphere: atmosphere lacking oxygen or other oxidizers
- reduction:
- reduction potential (Eh,ORP,pE): measure of a chemical species' tendency to acquire electrons
- reference direction:
- reference plane:
- reflecting telescope:
- reflection:
- earthshine: reflected and emitted electromagnetic radiation from Earth
- reflection nebula: nebula made visible by light it scatters from nearby stars
- reflection spectroscopy:
- reflector:
- reflector telescope: telescope using mirrors rather than lenses to magnify
- refraction:
- refractive index:
- refractive interstellar scintillation (RISS): refraction of star light by the ISM
- refractory:
- refractory compound:
- refractory element:
- refractory material: material with high condensation temperature
- regolith: loose solid material covering a planet's solid rock
- regolith scale:
- regolith: loose solid material covering a planet's solid rock
- regular moon:
- regular perturbation problem:
- regular satellite:
- reionization:
- relation:
- relative astrometry:
- astrometry: precise measurement of the position and movement of stars
- relative atomic mass:
- element: class of atom based on its number of protons
- relative humidity:
- humidity: amount of water vapor in a portion of the atmosphere
- relativistic beaming: directional relativistic effect on light from relativistic speeds
- relativistic energy: energy of an object including relativistic effects
- relativistic hydrodynamics:
- relativistic invariance: quantity that remains the same regardless of frame of reference
- relativistic jet:
- jet: stream of matter from an astronomical body
- relativistic magnetohydrodynamics:
- relativistic mass:
- mass: object's quality that determines the effects of forces and gravity
- relativistic momentum: momentum of an object including relativistic effects
- relativistic speed: a good fraction of the speed of light
- relativistic Sunyaev-Zel'dovich effect:
- relativity: physics models accommodating the constancy of the speed of light
- relaxation time:
- Stokes number (Stk,St): measure of a particle's tendency to flow the flow of a fluid
- relic abundance:
- relic neutrinos:
- Rem:
- Reynolds number (Re): measure reflecting a fluid system's propensity to turbulence
- Research Consortium On Nearby Stars:
- RECONS: consortium for research on stars near the Sun
- resistive MHD:
- resistivity:
- Reynolds number (Re): measure reflecting a fluid system's propensity to turbulence
- resolution:
- resolution convergence:
- Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics:
- ROCKE-3D: Rocky-planet-oriented general circulation model
- resolving power:
- spectral resolution (R): measure of a spectrograph's ability to resolve features of the spectrum
- resonance:
- Q factor: measure of oscillator's damping
- rest energy:
- rest frame:
- rest mass:
- mass: object's quality that determines the effects of forces and gravity
- relativistic energy: energy of an object including relativistic effects
- relativistic momentum: momentum of an object including relativistic effects
- rest wavelength: normal wavelength observed when not moving in relation to the source
- Restore-L: prototype space robot for servicing satellites
- restricted circular three body problem:
- retrieval: determining measures through observation and modeling
- retrieval code:
- retrieval: determining measures through observation and modeling
- retrograde hot Jupiter: large hot planet orbiting opposite the expected direction
- retrograde motion:
- epicycle: small circular motion around a large circular motion
- retrograde orbit: orbit opposite the usual direction
- retrograde rotation:
- Revised Luyten Half-second Catalog:
- REX:
- Reynolds decomposition: mathematical separation of average and fluctuating parts of a quantity
- Reynolds number (Re): measure reflecting a fluid system's propensity to turbulence
- Reynolds stress:
- RF:
- RFI:
- RG:
- RGB:
- RGS:
- XMM-Newton: x-ray observatory-satellite operated by ESA
- RGZ:
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- RHAPSODY-G:
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- RHCP:
- polarization: property of waves that oscillate in a particular direction
- RHD:
- Rhea:
- moon: a planet's natural satellite, such as Earth's
- Saturn: second largest planet in the solar system
- Rho Ophiuchi:
- Rho Ophiuchi Cloud Complex: nebula that is a nearby star-forming region
- LDN 1689: dense core within the Rho Ophiuchi Cloud Complex
- RHS:
- RHU:
- MMRTG: power source for space probes
- Ri:
- Richardson number (Ri): measure of fluid stability consisting of ratio of buoyancy and shear
- Richardson number (Ri): measure of fluid stability consisting of ratio of buoyancy and shear
- Riemann problem: consequence of discontinuities in numerical methods
- Rigel: brightest star in constellation Orion
- Orion: well-known constellation in the northern hemisphere
- right ascension (RA): direction coordinate along celestial equator
- right hand rule:
- right-hand circular polarization:
- polarization: property of waves that oscillate in a particular direction
- Rigil Kentaurus:
- RIMAS:
- RIME:
- JUICE: mission to Jupiter in development
- RIMFAX:
- ring:
- ring galaxy: ring-like galaxy, darker in the middle
- ring system: disk or set of rings orbiting a planet
- J1407: star orbited by a companion with a ring system
- Saturn: second largest planet in the solar system
- rings:
- ripper tines:
- CAESAR: planned space mission to return a sample of a comet
- rise azimuth:
- rise time:
- RISS:
- Ritchey-Chrétien telescope (RCT,RC): type of double reflecting telescope
- RM:
- RM effect:
- RMHD:
- RMS:
- RMS astronomy: collective term for radio, millimeter, and submillimeter
- RMS astronomy: collective term for radio, millimeter, and submillimeter
- rms wavefront error:
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- Ro:
- Robert C. Byrd Green Bank Telescope:
- Robertson-Walker metric:
- metric: mathematical generalization of the concept of distance
- Robertson-Walker scale factor:
- scale factor: relative size of the universe as a function of time
- RoboNet: global network of robotic telescopes to follow up on GRBs
- RoboNet-1.0:
- RoboNet: global network of robotic telescopes to follow up on GRBs
- RoboNet-II:
- RoboNet: global network of robotic telescopes to follow up on GRBs
- Robotic Optical Transient Search Experiment:
- ROTSE: automated array of telescopes to uncover and track transients
- Roche limit: nearest a body can orbit another and survive
- Roche lobe:
- Roche limit: nearest a body can orbit another and survive
- Roche radius:
- Roche limit: nearest a body can orbit another and survive
- rock:
- silicate: type of compound including silicon and oxygen
- rock vapor phase:
- ROCKE-3D: Rocky-planet-oriented general circulation model
- rocky planet: planet like Earth and Mars, mostly rock
- RODEO: code for 2d disk simulation
- ROE:
- Roe solver:
- RODEO: code for 2d disk simulation
- rogue planet:
- field: adjective meaning "in this field of view but unrelated"
- ROLIS:
- Rosetta: space probe that visited a comet
- Roma-BZCAT: 2013 catalog of blazars
- ROMAP:
- Rosetta: space probe that visited a comet
- root mean square:
- ROSAT: 1990s German space x-ray telescope
- ROSAT All Sky Survey:
- Rosat All-sky Survey:
- Rosat Bright Survey (RBS): list of bright X-ray sources from ROSAT observations
- ROSAT Deep Cluster Survey:
- ROSAT: 1990s German space x-ray telescope
- ROSAT Deep Survey:
- deep survey: survey using lengthy observation to identify distant galaxies
- ROSAT: 1990s German space x-ray telescope
- Rosat Hard Survey (RHS): list of hard X-ray sources from ROSAT observations
- Rosetta: space probe that visited a comet
- ROSINA:
- Rosetta: space probe that visited a comet
- Ross:
- Ross 128 b:
- Ross 154: nearby red dwarf
- Ross 248: nearby red dwarf
- Rossby deformation radius:
- Rossby number (Ro): ratio of inertial to Coriolis force
- Rossby radius of deformation: length scale where rotation effects are significant
- Rossby wave instability (RWI): type of disk instability that may be a factor in planet formation
- Rossby waves: meandors in high-altitude winds
- Rosseland mean:
- Rosseland mean opacity: a useful weighted average of opacities at all the wavelengths
- Rosseland optical depth:
- Rossi X-ray Timing Explorer:
- RXTE: space mission to time X-ray variations
- Rossiter-McLaughlin effect (RM effect,RM): effect of transit on visible spectrum of the star
- rotating radio transit:
- rotation:
- millisecond pulsar (MSP): pulsar spinning with a period in the range of milliseconds
- nutation: precession of a body's axis of rotation
- P-Pdot diagram: diagram comparing the rotation and the slowing of pulsars
- precession: periodic change in a body's rotation or orbit
- pulsar (PSR): astronomical body whose electromagnetic radiation displays a cycle
- rotation curve: function of orbital speed to orbital radius for a galaxy
- rotation measure:
- Faraday rotation: rotation of optical polarization by a medium in a magnetic field
- rotation period: time it takes an astronomical body to revolve
- rotation rate:
- rotational broadening:
- rotational modulation:
- rotational velocity:
- ROTSE: automated array of telescopes to uncover and track transients
- ROTSE-I:
- ROTSE: automated array of telescopes to uncover and track transients
- ROTSE-II:
- ROTSE: automated array of telescopes to uncover and track transients
- ROTSE-III:
- ROTSE: automated array of telescopes to uncover and track transients
- ROX:
- Royal University of Edinburgh:
- rp-process:
- RPC APXS:
- Rosetta: space probe that visited a comet
- RPWI:
- JUICE: mission to Jupiter in development
- RPWS:
- Cassini: explorer spaceship sent to Saturn
- RR Lyrae:
- RR Lyrae star:
- RR Lyrae variable: star with periodic variation often in globular clusters
- RS:
- radio source (RS): something in the sky generating radio signal
- RS Canum Venaticorum star:
- RS Canum Venaticorum variable:
- RSD:
- redshift space: concept of space using redshift as the radial dimension
- RSI:
- Rosetta: space probe that visited a comet
- RSR:
- RSS:
- Rsun:
- Sun: star at center of solar system
- rSZ:
- rSZE:
- RT:
- RT code:
- RT instability: result of lighter fluid pushing a heavier fluid
- RTE:
- RTM:
- RTSW:
- runaway accretion:
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- runaway greenhouse effect:
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- runaway growth:
- runaway star:
- Russia:
- Russian:
- Rutherford-Bohr model:
- Bohr model: has electrons circling nucleus in quantized orbits
- RV:
- RV method:
- Automated Planet Finder (APF): robotic telescope to find exoplanets using RV method
- CRIRES: high resolution IR echelle spectrometer
- extra-solar planet: planet not in the solar system
- HARPS: high-precision spectrograph for exoplanet searches
- HARPS-N: high-precision spectrograph for exoplanet searches in Canary Islands
- HD 209458 b: hot Jupiter discovered in 1999
- HD 80606 b: hot Jupiter discovered in 2001
- HRS: high resolution spectrography
- Keck Planet Finder (KPF): spectrograph in development for Keck
- minimum mass (m sin i): measured bound on the mass of an exoplanet
- NGC 3201: globular cluster in which a black hole has been identified
- PLATO: planned observatory-satellite aimed at finding exoplanets
- radial velocity (RV): component of velocity toward or away from observer
- RV observatory:
- RVS:
- Gaia: survey satellite at 400-1000 nanometers
- RWI:
- RX:
- ROSAT: 1990s German space x-ray telescope
- RXC:
- ROSAT: 1990s German space x-ray telescope
- RXTE: space mission to time X-ray variations
- Rydberg constant:
- Balmer series: hydrogen lines for electrons settling from n > 2 to n = 2
- Brackett series: hydrogen lines for electrons settling from n > 4 to n = 4
- Lyman series: hydrogen series from electrons settling from n > 1 to n = 1
- Paschen series: hydrogen lines for electrons settling from n > 3 to n = 3
index