What is the boundary between day and night on the Moon?

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In the movie "Running to the Stars", there is a clear line between day and night on the moon. Is this true or false?

There is a slight disagreement on the definitions of day and night. A day is the time from sunrise to sunset, but sunrise and sunset, like sunset, have two definitions. We will start from the following principle: sunrise begins when the sun begins to rise above the horizon and ends when the sun disappears completely out of view, and sunset begins when the sun begins to set below the horizon and ends when the sun completely disappears from view. 。

It's still in the movies.

In astronomy, the line separating the diurnal region of a celestial body is called the light-dark boundary, i.e., the twilight zoneAs the line of light and dark moves along the planet's surface, it smoothly transitions from day to night and vice versa. The width of the line between light and dark depends on many factors: the size of the object itself and the light source, the distance between them, and the presence of an atmosphere on the object that can scatter light in geometrically shaded areas.

Ideally, when the light source is a point and the object has no atmosphere, the boundaries are clear, fluctuate only on uneven terrain, and the transition from daytime to nighttime will be instantaneous. The Moon does not have an atmosphere, but the Sun is not a point light source, so only part of the disk will be visible from the area of the light-dark line, and the rest will be below the horizon, and the illumination will be weaker than when it is on the Moon. The sun is completely above the horizon.

The transformation of the lunar surface from day to night.

When a person moves from the nocturnal zone on the moon to the daytime zone, one will cross a clear boundary that separates the geometrically shaded area from the penumbra zone (where the light does not fall at all), which is at least the Terminator where the light falls, and this is the moment shown in the movie To the Stars, "To reach the daytime zone, it is still necessary to cross the line between light and dark, and the illumination will increase steadily." In general, there are a lot of inaccuracies about the question of where the sun is in ** and at what angle the rays of light fall in the scene of the trip to the lunar surface in the film, but this is a separate topic.

Moon Terminator.

On Earth, the boundary between light and dark is not very clear due to the scattering of light in the atmosphere, and as a result of this phenomenon, light falls into geometric shadow areas. It's hard for me to say how accurate the contrast between shadow and penumbra is in this film;It's hard to say what it's going to look like from the dry graphics, but the night side of the moon in this movie is what it should be like in reality, and the Terminator area is shallower, but the contrast between these areas should be about the same.