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Summer days are longer than winter days, but the difference is no more than approximately two and a half hours. The daily path of the Sun is steep at the horizon the whole year round, resulting in a twilight of only about one hour and 20 minutes in the morning and in the evening. Solstice day arcs as viewed from 50° latitude.
The Earth's axial tilt (called the obliquity of the ecliptic by astronomers) is the angle between the Earth's axis and a line perpendicular to the Earth's orbit. The Earth's axial tilt changes slowly over thousands of years but its current value of about ε = 23.44° is nearly constant, so the change in solar declination during one year is ...
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlight , starlight , and airglow , depending on location and timing.
The Sun appears larger at sunrise than it does while higher in the sky, in a manner similar to the Moon illusion. The Sun appears to rise above the horizon and circle the Earth, but it is actually the Earth that is rotating, with the Sun remaining fixed. This effect results from the fact that an observer on Earth is in a rotating reference frame.
Earth's terminator as seen from space. A terminator or twilight zone is a moving line that divides the daylit side and the dark night side of a planetary body.The terminator is defined as the locus of points on a planet or moon where the line through the center of its parent star is tangent.
The east–west component shows the equation of time, or the difference between solar time and local mean time. This can be interpreted as how much "ahead" or "behind" the Sun (or an analemmatic sundial) is compared to clock time. It also shows how far west or east the Sun is, compared with its mean position.
The video thus begins when the sun is slightly above the horizon and at an azimuth of 120°. The sky is highly polarized in the effective North-Zenith-South plane. This is slightly offset because the sun's azimuth is not due East. The sun moves across the sky with clear circular polarization patterns surrounding it.
Sky brightness refers to the visual perception of the sky and how it scatters and diffuses light. The fact that the sky is not completely dark at night is easily visible. If light sources (e.g. the Moon and light pollution ) were removed from the night sky , only direct starlight would be visible.