the shape of earth's orbit around the sun is elliptical.
the shape of earth's orbit around the sun is elliptical.
the shape of earth's orbit around the sun is?
elliptical
unfortunately, the earth does not make a perfect circular orbit around the sun. due to the elliptical nature of the earth’s orbit around the sun, the speed of the sun’s apparent orbit around the earth varies throughout the year and that causes it to appear to speed up and slow down very slightly. consequently, noon at the prime meridian is rarely if ever exactly at 1200 utc, but rather it occurs some minutes and seconds before or after that time each day. this slight daily variation has been calculated and is listed for each day of the year in the nautical almanac under the title of "equation of time". this variation must be added to or subtracted from the utc of local apparent noon to improve the accuracy of the calculation. even with that, other factors, including the difficulty of determining the exact moment of local apparent noon due to the flattening of the sun’s arc across the sky at its highest point, diminish the accuracy of determining longitude by chronometer as a method of celestial navigation. accuracies of less than error in position are difficult to achieve using the "longitude by chronometer" method. other celestial navigation methods involving more extensive use of both the nautical almanac and sight reduction tables are used by navigators to achieve accuracies of one nautical mile (1.9 km) or less.
longitude by chronometer
bullet::::- geocentric orbit: an orbit around the planet earth, such as that of the moon or of artificial satellites.









































bullet::::- lunar orbit (also selenocentric orbit): an orbit around earth's moon.









































bullet::::- areocentric orbit: an orbit around the planet mars, such as that of its moons or artificial satellites.









































for orbits centered about planets other than earth and mars, the orbit names incorporating greek terminology is less commonly used









































bullet::::- mercury orbit (hermocentric or hermiocentric): an orbit around the planet mercury.









































bullet::::- venus orbit (aphrodiocentric or cytheriocentric): an orbit around the planet venus.
list of orbits