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v. t. e. Satellite geodesy is geodesy by means of artificial satellites —the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth 's gravity field by means of artificial satellite techniques. It belongs to the broader field of space geodesy.
A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a derivation from the Moon of Earth . In the Solar System, there are six planetary satellite systems containing ...
World map. A world map is a map of most or all of the surface of Earth. World maps, because of their scale, must deal with the problem of projection. Maps rendered in two dimensions by necessity distort the display of the three-dimensional surface of the Earth.
The orbit of the Moon is a nearly circular ellipse about the Earth (the semimajor and semiminor axes are 384,400 km and 383,800 km, respectively: a difference of only 0.16%). The equation of the ellipse yields an eccentricity of 0.0549 and perigee and apogee distances of 362,600 km (225,300 mi) and 405,400 km (251,900 mi) respectively (a ...
Real-time kinematic positioning ( RTK) is the application of surveying to correct for common errors in current satellite navigation (GNSS) systems. It uses measurements of the phase of the signal's carrier wave in addition to the information content of the signal and relies on a single reference station or interpolated virtual station to ...
First full-disk "true color" [41] picture of the Earth; [42] subsequently used on the cover of the first Whole Earth Catalog. [43] [42] December 21, 1968. Apollo 8. First full-disk image of Earth from space taken by a person, probably by astronaut William Anders. [44] December 24, 1968.
Sun–Earth L4. L 4 is the Sun–Earth Lagrange point located close to the Earth's orbit 60° ahead of Earth. Asteroid 2010 TK 7 is the first discovered tadpole orbit companion to Earth, orbiting L 4; like Earth, its mean distance to the Sun is about one astronomical unit. Asteroid 2020 XL 5 is the second Earth trojan, confirmed in November ...
Line-of-sight propagation. Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. [1] Electromagnetic transmission includes light emissions traveling in a straight line.