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In other words, the celestial equator is an abstract projection of the terrestrial equator into outer space. [1] Due to Earth's axial tilt , the celestial equator is currently inclined by about 23.44° with respect to the ecliptic (the plane of Earth's orbit ), but has varied from about 22.0° to 24.5° over the past 5 million years [ 2 ] due ...
Modified from azimuthal equal-area equatorial map. Boundary is 2:1 ellipse. Variants are oblique versions, centred on 45°N. 1994 Strebe 1995: Pseudoazimuthal Equal-area Daniel "daan" Strebe Formulated by using other equal-area map projections as transformations. 1921 Winkel tripel: Pseudoazimuthal Compromise Oswald Winkel
The following table lists the common coordinate systems in use by the astronomical community. The fundamental plane divides the celestial sphere into two equal hemispheres and defines the baseline for the latitudinal coordinates, similar to the equator in the geographic coordinate system.
Certain reference lines and planes on Earth, when projected onto the celestial sphere, form the bases of the reference systems. These include the Earth's equator, axis, and orbit. At their intersections with the celestial sphere, these form the celestial equator, the north and south celestial poles, and the ecliptic, respectively. [8]
The other two cover the equatorial region of the celestial sphere, from the declination of 30° south to 30° north. The two equatorial charts are mercator projections, one for the eastern hemisphere of the celestial sphere and one for the western hemisphere. Note that unlike familiar maps, east is shown to the left and west is shown to the right.
The Atlas Coeli covers both hemispheres with 16 charts. The coordinate system is referred to equinox 1950.0 and the scale is 1° = 0.75 cm. There are six charts of the equatorial regions on a rectangular graticule, covering declinations from +25° to -25°; four charts for each hemisphere with straight, converging hour circles and concentric, equally-spaced declination circles covering ...
The plane of Earth's equator, when projected outwards to the celestial sphere, defines the celestial equator. In the cycle of Earth's seasons, the equatorial plane runs through the Sun twice a year: on the equinoxes in March and September. To a person on Earth, the Sun appears to travel along the equator (or along the celestial equator) at ...
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...