Sunrise also known as sun up refers to the moment when the upper limb of the sun appears on the horizon and marks the start of morning. This term might also refer to the entire process of the solar disk crossing the horizon and its corresponding atmospheric effects. Even though, to one the sun may appear rising in the sky, in actual fact it is the Earth's motion that causes the sun to appear. As ons sees the sun moving, it is to note that this is an illusion as the observer is standing in a rotating reference frame, that results from the rotation of the Earth. To many this apparent motion is so convincing that some cultures had mythologies and religions built around the geocentric model. This model continued to play until astronomer Nicolaus Copernicus formulated his heliocentric model in the 16th century.
The terms of sunsight and sunclipse were proposed by the famous architect Buckminster Fuller, in order to better represent the heliocentric model, though these terms have not entered the world of common language. Defining astronomically, sunrise occurs only for an instant, the exact moment at which the upper limb of the Sun comes to be tangent to the horizon.
In this sub category you can download free PNG images: Sunrise Nature. In this category "Sunrise" we have 6 free PNG images with transparent background.