The dividing line between the illuminated and the unilluminated part of the moon.

The line separating the illuminated and unilluminated parts of a celestial body; the dividing line between day and night as observed from a distance.

The line between nighttime and daytime on a moon or planet; the edge of the part of a moon or planet that is lighted by the sun.

The dividing line between the illuminated and shadowed portions of the lunar or planetary disk.

The boundary between the half of the Earth that has daylight and the half experiencing night.

the boundary between the illuminated and dark areas of the apparent disk of the Moon, a planet or a planetary satellite.

The line separating the illuminated and the darkened areas of a body such as the Earth or Moon which is not self-luminous.

An imaginary, diffuse line separating the illuminated and dark portions of a celestial body. There are two terminators: morning and evening.

The boundary between the lighted and unlighted portions of a celestial body's surface.

The boundary of the illuminated part of the disc of a planet or moon.

The transition line from day to night. Only seen on visual imagery.

the boundary between the illuminated and dark areas of the Moon or other planetary body

The boundary on a celestial object separating day from night.

Boundary area between the lit and dark areas of the moon or planet.

The boundary line on a planet or satellite between the dark side and the sunlit side.

The boundary between day and night regions of the moon's, or a planet's, disc.

the boundary on a planet or moon separating the illuminated side from the unilluminated.

The boundary between the light side and the dark side of a planet or other body.

The (imaginary) line separating the lighted and dark portions of a celestial body that is being lit by the Sun. Ex. The terminator line between illuminated and dark sides of the Moon as it proceeds through its monthly phases.

A distinct shadow edge that marks the boundary between the night and day side of a moon or planet. Because of shadows cast along this jagged boundary on the Moon, it is easy to see the three-dimensionality of lunar mountains and craters. Sometimes, towering crater rings still catch a bit of sunlight as they slip behind the terminator.

The line of sunrise or sunset on a planet or its satellite. At dawn and dusk when the sun is lowest in the sky (low sun), topographic features cast their longest shadows. This reveals information about the size and shape of the objects casting the shadows. Therefore, features near the terminator are imaged in order to obtain morphologic information. (see High sun)

Terminators define the boundary of an architecture. The National ITS Architecture terminators represent the people, systems, and general environment that interface to ITS. The interfaces between terminators and the subsystems and processes within the National ITS Architecture are defined, but no functional requirements are allocated to terminators. The logical architecture and physical architecture views of the National ITS Architecture both have exactly the same set of terminators. The only difference is that logical architecture processes communicate with terminators using data flows, while physical architecture subsystems use architecture flows. Select "Physical Architecture" from the main menu and then either select "Terminators" in the page title or scroll down past the list of subsystems to the list of all terminators. View a sample Terminator Page.

The terminator is the day-night line on a planet (or other body).

The great circle of transition from daylight to darkness on the earth's surface. The terminator appears in visible environmental satellite imagery as a gradual change from easily detectable cloud features to nearly black imagery.

The terminator is the line between the illuminated, day side and dark, night side of a planetary body (also known as the "grey line" or the "twilight zone"). It is defined as the locus of points on a moon or planet where the line through the sun is tangent. The line separates the portions of the earth experiencing daylight from the portion of the planet experiencing darkness.