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Sun path, sometimes also called day arc, refers to the daily (sunrise to sunset) and seasonal arc-like path that the Sun appears to follow across the sky as the Earth rotates and orbits the Sun. The Sun's path affects the length of daytime experienced and amount of daylight received along a certain latitude during a given season.
The Sun's path changes with its declination during the year. The intersections of the curves with the horizontal axis show azimuths in degrees from North where the Sun rises and sets. The Sun appears to move northward during the northern spring, crossing the celestial equator on the March equinox.
Also, unlike most other solar measurements, sunrise occurs when the Sun's upper limb, rather than its center, appears to cross the horizon. The apparent radius of the Sun at the horizon is 16 arcminutes. [1] These two angles combine to define sunrise to occur when the Sun's center is 50 arcminutes below the horizon, or 90.83° from the zenith. [1]
The Sun is a rotating sphere of plasma at the center of the Solar System. It lacks a solid or liquid surface, so the interface separating its interior and its exterior is usually defined as the boundary where plasma becomes opaque to visible light, the photosphere.
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The Sun is the star at the center of the Solar System.It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies.
The detailed images recorded by SDO in 2011–2012 have helped scientists uncover new secrets about the Sun. The Solar Dynamics Observatory (SDO) is a NASA mission which has been observing the Sun since 2010. [4] Launched on 11 February 2010, the observatory is part of the Living With a Star (LWS) program. [5]
The Sun, in its apparent motion along the ecliptic, crosses the celestial equator at these points, one from south to north, the other from north to south. [6] The crossing from south to north is known as the March equinox, also known as the first point of Aries and the ascending node of the ecliptic on the celestial equator. [10]