Sunset from Umang Island (2)

Sunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.

The time of sunset is defined in astronomy as the moment when the trailing edge of the Sun's disk disappears below the horizon in the west. The ray path of light from the setting Sun is highly distorted near the horizon because of atmospheric refraction, making the sunset appear to occur when the Sun’s disk is already about one diameter below the horizon. Sunset is distinct from dusk, which is the moment at which darkness falls, which occurs when the Sun is approximately eighteen degrees below the horizon. The period between sunset and dusk is called twilight.

Locations north of the Arctic Circle and south of the Antarctic Circle experience no sunset or sunrise at least one day of the year, when the polar day or the polar night persist continuously for 24 hours.

Sunset creates unique atmospheric conditions such as the often intense orange and red colors of the Sun and the surrounding sky.

A tree is a perennial woody plant. It most often has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to 6 m; some authors set a minimum of 10 cm trunk diameter (30 cm girth). Woody plants that do not meet these definitions by having multiple stems and/or small size are usually called shrubs, although many trees such as Mallee do not meet such definitions. Compared with most other plants, trees are long-lived, some reaching several thousand years old and growing to up to 115 m (379 ft) high.

Trees are an important component of the natural landscape because of their prevention of erosion and the provision of a weather-sheltered ecosystem in and under their foliage. They also play an important role in producing oxygen and reducing carbon dioxide in the atmosphere, as well as moderating ground temperatures. They are also elements in landscaping and agriculture, both for their aesthetic appeal and their orchard crops (such as apples). Wood from trees is a building material, as well as a primary energy source in many developing countries. Trees also play a role in many of the world's mythologies (see trees in mythology).

A silhouette is the image of a person, an object or scene represented as a solid shape of a single color, usually black, its edges matching the outline of the subject. The interior of a silhouette is basically featureless, and the whole is typically presented on a light background, usually white, or none at all. The silhouette differs from an outline which depicts the edge of an object in a linear form, while a silhouette appears as a solid shape. Silhouette images may be created in any visual artistic media.

Cutting portraits, generally in profile, from black card became popular in the mid-18th century, though the term “silhouette” was seldom used until the early decades of the 19th century, and the tradition has continued under this name into the 21st century. From its original graphic meaning, the term "silhouette" has been extended to describe the sight or representation of a person, object or scene that is backlit, and appears dark against a lighter background. Anything that appears this way, for example, a figure standing backlit in a doorway, may be described as "in silhouette". Because a silhouette emphasises the outline, the word has also been used in the fields of fashion and fitness to describe the shape of a person's body or the shape created by wearing clothing of a particular style or period.

Contre-jour, French for 'against daylight', refers to photographs taken when the camera is pointing directly toward a source of light. An alternative term is backlighting.

Contre-jour produces backlighting of the subject. This effect usually hides details, causes a stronger contrast between light and dark, creates silhouettes and emphasizes lines and shapes. The sun, or other light source, is often seen as either a bright spot or as a strong glare behind the subject. Fill light may be used to illuminate the side of the subject facing toward the camera. Silhouetting occurs when there is a lighting ratio of 16:1 or more; at lower ratios such as 8:1 the result is instead called low-key lighting.