optical phenomenon
observable event that results from the interaction of light and matter
horizon
apparent line that separates earth from sky
moon dog
bright spot on a lunar halo
luminescence
emission of light by a substance not resulting from heat
depth of field
distance between the nearest and the furthest objects that are in focus in an image
Tyndall effect
light scattering by particles in a colloid
fog bow
type of rainbow formed by airborne water droplets
gegenschein
faint brightening of the night sky in the region of the antisolar point
evanescent wave scattering
optical phenomenon
opalescence
optical iridescence phenomena characteristic of the opal gemstone
Arago spot
bright point that appears at the center of a circular object's shadow due to Fresnel diffraction
parallax
difference in the apparent position of an object viewed along two different lines of sight
Baily's beads
feature of total and annular solar eclipses
vignetting
reduction of an image's brightness or saturation toward the periphery compared to the image center
earthquake light
optical phenomenon
diamond ring effect
bright spot on the lunar edge since for a few seconds during a solar eclipse
slow light
propagation of an optical pulse at a very low group velocity
sun glitter
sparkling light formed when sunlight reflects from water waves
sunny
type of weather
circle of confusion
blurry region in optics
light scattering
physical processes where moving particles or radiation (e.g. light or sound), deviate from a straight trajectory by localized non-uniformities
impossible color
color that cannot be perceived under ordinary viewing conditions
lustre
manner in which light interacts with a crystal, rock, or mineral's surface
diffuse sky radiation
Solar radiation scattered and absorbed in Earth's atmosphere
Airy disk
diffraction pattern in optics
colorless
having no color, either by transparency or by lack of pigment
dichromatism
phenomenon where a material's hue is dependent on properties of the substance
Non-reversing mirror
mirror that shows a non-reversed image
aurora
natural light display that occurs in the sky, primarily at high latitudes (near the Arctic and Antarctic on Earth) or even on other planets
pleochroism
optical phenomenon in which a substance appears to be different colors when observed at different angles, especially with polarized light
iridescence
property in which fine colors, changeable with the angle of view or angle of illumination, are produced on a surface by the interference of light that is reflected from both the front and back of a thin film
transient lunar phenomenon
short-lived light, color, or change in appearance on the surface of the Moon
Abney effect
perceived hue shift when white light is added to a monochromatic light source
fine weather
clear sky with no rain, no fog, and no thunderstorm, etc.
atmospheric optical phenomenon
interaction of light from the sun or moon with gases, clouds, water, dust and other particulates in the atmosphere
color
characteristic of visual perception
reflection
change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated
zodiacal light
glow in the night sky appearing to extend from the Sun's direction and along the zodiac
optical aberration
phenomenon in astronomy
spectral line
optical phenomenon
Hidden faces
perception or recognition of faces in something essentially different
alpenglow
optical phenomenon in which a horizontal red glowing band is observed on the horizon opposite to the sun
Brocken spectre
magnified shadow of an observer cast upon clouds opposite the Sun's direction
diffraction spike
lines radiating from bright light sources in photographs
extinction cross
optical phenomenon
asterism
ornamental stones that exhibit a luminous star when cut en cabochon
four-wave mixing
nonlinear optics intermodulation phenomenon whereby interactions between two or three wavelengths produce two or one new wavelengths