Astrophysics (Index)About

visible light

(light)
(electromagnetic radiation that our eyes can sense)

Visible light (or light) is electromagnetic radiation (EMR) that our eyes can sense, i.e., visible to us. Cited wavelength ranges vary somewhat: a representative example is 390 to 750 nm, corresponding to EMR frequencies between 400 and 769 THz. The colors we sense depend upon the wavelengths of the light. EMR of longer wavelength than visible light is termed infrared (having wavelengths longer than that of red light) and shorter than visible light, ultraviolet (with wavelengths shorter than that of violet light). Visible light is a tiny portion of the spectrum of EMR around us, with a much smaller wavelength-range than the other well-known categories (ultraviolet, radio, etc.), but is naturally of particular interest to us since we sense it. The brightest portion of the Sun's spectrum is visible light, one reason our eyes are adapted to use it, and it falls within an Earth atmospheric window, i.e., the atmosphere is transparent to it; atmosphere blocks much of the rest of the electromagnetic spectrum from reaching us from space. The word optical is often used to indicate visible light when describing/name an astronomical survey, observation, instrument, or telescope, but is also commonly used for the portions of infrared and ultraviolet for which equipment (e.g., telescope mirrors) is identical or similar.

Visible-light observation (optical astronomy) was the entirety of astronomy for millennia and it has only been in the 20th century that astronomy began to do more, beginning with the discovery of radio sources, and with the use of visible-light telescopes to image the portions of the ultraviolet and infrared adjacent to visible light. Visible light is also the primary type of observation by amateur astronomers, and casual astronomical viewing, such as back-yard astronomy. In the past, astronomy was basically the study of the visible night sky, with the pattern of relative movements of the stars, planets, and Moon, and their positions relative to the Sun. Weather has always been a challenge to visible-light viewing and light pollution is now a serious challenge. Viewing from high altitudes offer advantages, for optical astronomy as well as most other types of astronomical observation.


(EMR,spectrum,band)
Further reading:
https://en.wikipedia.org/wiki/Visible_light
https://en.wikipedia.org/wiki/Visible-light_astronomy
https://en.wikipedia.org/wiki/Visible_spectrum
https://astronomy.swin.edu.au/cosmos/l/Light
http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html#c2
https://sites.uni.edu/morgans/astro/course/Notes/section1/new4.html
https://web.njit.edu/~gary/202/Lecture5.html
https://ecampus.matc.edu/mihalj/astronomy/test3/physics_of_light.htm
WaveLFreqPhoton
Energy
  
390nm769THz3.2eVbeginvisible light
750nm400THz1.7eVendvisible light

Referenced by pages:
2175 angstrom feature
3C 273
3C 279
3C 295
3C 348
3C 48
4MOST
A-type star (A)
aberration
absolute magnitude (M)
absorption
absorption coefficient
active galactic nucleus (AGN)
active galaxy
adaptive optics (AO)
Airy disk
albedo
angstrom (Å)
angular resolution
antenna pattern
aperture
aperture masking interferometry (AMI)
aperture photometry
aperture synthesis
apodization
apparent magnitude (m)
astronomical quantities
AstroSat
Atacama Cosmology Telescope (ACT)
atmosphere
atmospheric window
aurora
BA supergiant
Balmer series (H)
bandpass filter
bar
BASS
beam
Big Bear Solar Observatory (BBSO)
biofluorescence
black body (BB)
black hole (BH)
black hole shadow
black-body radiation
BlackGEM
blended spectra
Boötes Field
bolometric correction
bolometric magnitude (Mbol)
bright nebula
Calar Alto Observatory
Canada-France-Hawaii Telescope (CFHT)
Cassegrain reflector
CCD
Cederblad Catalog (Ced)
chopping mirror
chromatic aberration
CMB dipole
COAST
coherent light
COLD GASS
collimator
color temperature (TC)
Colossus Telescope
Compton telescope
confusion limit
convolution
core collapse supernova (CCSN)
corona
coronagraph
correlator
Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)
cosmic background radiation (CBR)
cosmic dust
cosmic infrared background (CIB)
cosmic microwave background (CMB)
cosmic optical background (COB)
cosmological principle
cosmological time dilation
coudé focus telescope
counterpart
curvature radiation
Cygnus-X
Danjon astrolabe
dark age
Dark Energy Survey (DES)
dark sky
Dawn
differential spectroscopy
diffraction
diffraction spike
DISCOVR
DKIST
Doppler shift
Dragone telescope
Dragonfly Telephoto Array
dropout
earthshine
eclipsing binary (E)
effective radius (Re)
electromagnetic radiation (EMR)
electromagnetic spectrum
electromagnetism (EM)
elevation range
emission
emission nebula
Euclid
European Extremely Large Telescope (E-ELT)
European Southern Observatory Very Large Telescope (ESO VLT)
exoplanet eclipse light curve
exosatellite
extinction
extragalactic background light (EBL)
extreme adaptive optics (ExAO)
extreme ultraviolet (EUV)
extremely red object (ERO)
F-type star (F)
Fabry-Pérot interferometer (FPI)
far infrared (FIR)
Faraday rotation
Fenton Hill Observatory (FHO)
fiber positioner
filter
filter bank
fluorescence
focal length
focal plane array (FPA)
Fraunhofer lines
FRB121102
frequency (ν)
G band (G)
G-CLEF
G-type star (G)
Gaia
Gaia Celestial Reference Frame (Gaia-CRF3)
GaiaNIR
galaxy classification
Gemini Observatory
geodesic
Giant Magellan Telescope (GMT)
Giotto
Gould's Belt Distances Survey (GOBELINS)
Gran Telescopio Canarias (GTC)
GRANAT
grating
gravitational lensing
gravitational microlensing
gravitational redshift
gravitational wave strain (h)
gravity
GRB-supernova (GRB-SN)
greenhouse effect
H-alpha (Ha)
H-beta (Hβ)
Hanbury Brown and Twiss effect (HBT effect)
HARMONI
Hawaii K-band Galaxy Survey
HCI
helium 1083 nm line
HERMES
Hewitt & Burbidge Catalog (HB87)
Hipparcos Celestial Reference Frame (HCRF)
Hobby-Eberly Telescope (HET)
Holmberg radius (RH)
Hubble Space Telescope (HST)
I band
illumination
image stabilization
imaging Fourier transform spectroscopy (IFTS)
infrared (IR)
INTEGRAL
intensity interferometer
interference
interferometer
interferometry
International Celestial Reference System (ICRS)
IOTA
IRTF
Isaac Newton Group of Telescopes (ING)
jansky (Jy)
jet
JUICE
Juno
K band
K-type star (K)
Kamioka Observatory
Keck Observatory
Kepler-Swift Active Galaxies and Stars Survey (KSwAGS)
KID
Kramers opacity law
Large Altazimuth Telescope (BTA-6)
Large Binocular Telescope (LBT)
Las Cumbres Observatory (LCO)
light cone
light curve
light echo
light pollution
light-year (ly)
limb darkening
line broadening
Livermore Optical Transient Imaging System (LOTIS)
Liverpool Telescope (LT)
Lorentz transformation
Lowell Discovery Telescope (LDT)
Lucy
LUVOIR
Lyman break (LB)
Lyot coronagraph (CLC)
Lyot stop
Magellan Telescopes
magnetic arcade
magnitude
Mars Polar Lander (MPL)
maser
mass spectrometer
mass-to-light ratio (M/L)
Maxwell's equations
MeerKAT
MeerLICHT
meteoroid
Michelson interferometer
Mie scattering
millimeter astronomy
MMT
MMX
moon
MOST
Mount Wilson Observatory (MWO)
MRO Interferometer (MROI)
multi-messenger astronomy (MMA)
Multi-object Optical and Near-IR Spectrograph (MOONS)
Multiwavelength Survey by Yale-Chile (MUSYC)
Munich Near-Infrared Cluster Survey (MUNICS)
N-body simulation
Nasmyth telescope
National Optical Astronomy Observatory (NOAO)
near infrared (NIR)
nebula
NEO Surveyor
neutrino (ν)
New Technology Telescope (NTT)
Newtonian telescope
nitrogen (N)
NOIRLab
observational astronomy
observatory (obs.)
occultation observations
occulting bar
OGLE
OH/IR source
OIR
Olbers' paradox
opacity (κ)
optical double
optical interferometer
optical transient (OT)
optics
Orbiting Wide-angle Light Collectors (OWL)
Orion Disks
OSO 7
PanCET
panchromatic
parsec (pc)
particle horizon
passband
PESSTO
phase angle
phase plate
photochemistry
photometry
photomultiplier tube (PMT)
photon
photosphere
Pi of the Sky
plane-parallel atmosphere
planetary nebula (PN)
plate measuring machine (APM)
point-spread function (PSF)
polarization
Poynting vector (S)
Poynting-Robertson effect
pressure integral
primary mirror
pulsar wind nebula (PWN)
PUNCH
quantum mechanics (QM)
quasar (QSO)
radial velocity method
Radio Camera Initiative (RCI)
radio telescope
radiometer equation
Rapid Eye Mount Telescope (REM)
RAPTOR
Rayleigh scattering
red noise
reddening
reflection nebula
reflector telescope
refraction
refractive index
relativity
Rosetta
Rossiter-McLaughlin effect (RM effect)
ROTSE
Schiefspiegler
Schmidt-Newton telescope (SNT)
scintillator
Seyfert galaxy (Sy)
SkyMapper
Sloan 2.5m Telescope
slowly-pulsating B-star (SPB)
SN 1987A (1987A)
Snell's law
SOAR Telescope (SOAR)
source function (S)
Southern African Large Telescope (SALT)
spacetime diagram
specific intensity
speckle masking
speckle suppression
speckles
spectral energy distribution (SED)
spectral line
spectral power distribution (SPD)
spectral resolution
spectrograph
spectrometer
spectropolarimetry
spectroscope
spectroscopic binary (SB)
spectroscopy
speed of light (c)
spherical aberration
star formation rate (SFR)
STARSMOG
stellar atmosphere
stellar distance determination
stellar structure
Strömgren photometric system
stray light
Strehl ratio
Subaru PFS
Subaru Telescope
SUNRISE
SuperBIT
superluminal motion
supernova light curve (SN light curve)
supernova remnant (SNR)
surface of last scattering
surface temperature
Swift
T Tauri
telescope
Telescope Array Project (TA)
Telescopio Nazionale Galileo (TNG)
Terrestrial Time (TT)
Thirty Meter Telescope (TMT)
TRACE
transient astronomy
transit telescope
transiting planet
Two Micron All-sky Survey (2MASS)
two-stream approximation
Type Ia supernova
U
ultraviolet (UV)
ultraviolet astronomy
Uranus Orbiter and Probe
UVOIR
V
variable star
Vega system
vegetation red edge (VRE)
Venus Express
VERITAS
Virgo
VISTA
wavelength (λ)
WFC3
wide binaries (WB)
Wide-field Infrared Survey Explorer (WISE)
Wien's displacement law
William Herschel Telescope (WHT)
WINGS
WIYN 3.5m Telescope
X-ray luminous galaxy cluster
XBONG
XMM-Newton
Yolo telescope
zodiacal light

Index