Question: Where is the starting meridian for the longitude system on the world map?

title: National Register of Historic Places listings in Jasper County, South Carolina
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Jasper County, South Carolina, United States. The locations of National Register properties, for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Jones County, South Dakota
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Jones County, South Dakota, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Lonoke County, Arkansas
text: This is intended to be a complete list of the properties and districts on the National Register of Historic Places in Lonoke County, Arkansas, United States. The locations of National Register properties and districts for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Tensas Parish, Louisiana
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Tensas Parish, Louisiana, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Surry County, North Carolina
text: This list includes properties and districts listed on the National Register of Historic Places in Surry County, North Carolina, United States. Click the "Map of all coordinates" link to the right to view a Google map of all properties and districts with latitude and longitude coordinates in the table below.

title: National Register of Historic Places listings in Lincoln County, Kansas
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Lincoln County, Kansas, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Susquehanna County, Pennsylvania
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Susquehanna County, Pennsylvania, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Carter County, Kentucky
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Carter County, Kentucky, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Adair County, Oklahoma
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Adair County, Oklahoma, United States. The locations of National Register properties for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Columbia County, Pennsylvania
text: This is intended to be a complete list of the properties and districts on the National Register of Historic Places in Columbia County, Pennsylvania, United States. The locations of National Register properties and districts for which the latitude and longitude coordinates are included below, may be seen in a map.

title: National Register of Historic Places listings in Butte County, Idaho
text: This is intended to be a complete list of the properties on the National Register of Historic Places in Butte County, Idaho, United States. Latitude and longitude coordinates are provided for many National Register properties and districts; these locations may be seen together in a map.

title: Murchison (crater)
text: Murchison is a lunar impact crater on the north edge of the Sinus Medii. It was named in honour of the geologist Sir Roderick Murchison. It shares a section of rim with the crater Pallas. To the southeast on the mare is the circular crater Chladni, and to the northeast is Ukert. Farther to the east is the prominent Triesnecker. Murchison lies astride the lunar zenith line, i.e. the starting longitude of the selenographic coordinate system.

title: Greenwich Mean Time
text: As the United Kingdom grew into an advanced maritime nation, British mariners kept at least one chronometer on GMT to calculate their longitude from the Greenwich meridian, which was by convention considered to have longitude zero degrees, internationally adopted in the International Meridian Conference of 1884. Synchronisation of the chronometer on GMT did not affect shipboard time, which was still solar time. But this practice, combined with mariners from other nations drawing from Nevil Maskelyne's method of lunar distances based on observations at Greenwich, led to GMT being used worldwide as a standard time independent of location. Most time zones were based upon GMT, as an offset of a number of hours (and possibly a half - hour) ``ahead of GMT ''or`` behind GMT''.

title: North Pole
text: The North Pole is the northernmost point on the Earth, lying diametrically opposite the South Pole. It defines geodetic latitude 90 ° North, as well as the direction of true north. At the North Pole all directions point south; all lines of longitude converge there, so its longitude can be defined as any degree value. Along tight latitude circles, counterclockwise is east and clockwise is west. The North Pole is at the center of the Northern Hemisphere.

title: Montes Alpes
text: Montes Alpes is a mountain range in the northern part of the Moon's near side. It was named after the Alps in Europe; the name was confirmed by the International Astronomical Union in 1935. It lies between the selenographic coordinates latitudes 52.81°N and 42.04°N, and longitudes 5.6°W and 3.22°E. The range thus crosses the lunar prime meridian, and is partially illuminated and partially in shadow during first and last quarters. The center of the range is at 48.36°N, 0.58°W, and has a diameter of 334 km.

title: Airy-0
text: Airy-0: Airy-0 is a crater on Mars whose location defined the position of the prime meridian of that planet. It is about across and lies within the larger crater Airy in the region Sinus Meridiani. The IAU Working Group on Cartographic Coordinates and Rotational Elements has now recommended setting the longitude of the Viking 1 lander (47°.95137 west) as the standard. This deﬁnition maintains the position of the center of Airy-0 at 0° longitude, within the tolerance of current cartographic uncertainties.

title: Choctaw meridian
text: The Choctaw meridian is a meridian that governs the surveys in most of central Mississippi, USA. It begins on the Choctaw baseline, latitude 31° 54' 40" north, longitude 90° 14' 45" west from Greenwich and runs north to the south boundary of the Chickasaw cession, at latitude 34° 19' 40" north.

title: Prime meridian
text: A prime meridian is a meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0 °. Together, a prime meridian and its antimeridian (the 180th meridian in a 360 ° - system) form a great circle. This great circle divides the sphere, e.g., Earth, into two hemispheres. If one uses directions of East and West from a defined prime meridian, then they can be called the Eastern Hemisphere and the Western Hemisphere.

title: Prime meridian
text: On Earth, starting at the North Pole and heading south to the South Pole, the IERS Reference Meridian (as of 2016) passes through:

title: Meridian (geography)
text: A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude. The position of a point along the meridian is given by its latitude indicating how many degrees north or south of the Equator the point is. Each meridian is perpendicular to all circles of latitude. Each is also the same length, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km (12,429.9 miles).

Answer: latitude 90 ° North