The Coast News Group
Coastal Cosmos

Putting San Diego on the map

No matter how deep you dig that hole on the beach, you will not reach China.If you were to astonishingly succeed in digging through the Earth, you would end up in the Indian Ocean, directly east of South Africa.The spot directly opposite a point on Earth is called the antipode.

Identifying the exact location of points on the Earth’s surface is a science vital to communication, commerce and transportation. Humans draw lines on maps to represent different positions across the globe.

Longitude is based on the angle that a point is to the east or west of the Prime Meridian (0 degrees), established in 1851 at the Royal Observatory, Greenwich in London. Latitude is measured as the angle north or south of the equator (0 degrees). Image courtesy of NASA

The geographic coordinates for Encinitas are 33 degrees 2 minutes 13 seconds-north and 117 degrees 17 minutes 31 seconds-south.

The geographic coordinate system allows all points on Earth to be recognized as a set of numbers. When looking at a map, east and west are represented as lines of longitude, also known as meridians. North and south are denoted as lines of latitude, also known as parallels.

Longitude is based on the angle that a point is to the east or west of the Prime Meridian (0 degrees), established in 1851 at the Royal Observatory, Greenwich in London. Latitude is measured as the angle north or south of the equator (0 degrees). Minutes of arc and seconds or arc are used to pinpoint exact locations. There are 60 minutes in each degree and 60 seconds in each minute.

We live in the North and Western Hemispheres because we are north of the equator and west of Greenwich. It is curious that lines running north/south measure the coordinates for east/west and vice versa.

Your smartphone knows where you are because it is receiving coordinate data from at least 4 Global Positioning Satellites at any given time. There are currently 31 GPS satellites orbiting the Earth. The first, NAVSTAR 1 was launched in 1978.

Meridians and parallels as arbitrary, human creations impact everything from national borders to our concept of time.

The border of the United States and Canada mostly runs along the 49 degrees parallel. All of our watches are set to Coordinated Universal Time (UTC), a successor to Greenwich Mean Time (GMT). Our concept of time is based on established time zones created in relation to the Prime Meridian in Greenwich. San Diego is in the Pacific Time Zone — 7 hours west of Greenwich as the Earth spins and the Sun brings new days.

Longitude and latitude have an enormous influence on the properties of the Earth’s surface.

The geographic coordinates of San Diego County impact the meteorology, geology, ecology, anthropology and oceanography. At about 33 degrees N 117 degrees S, San Diego is the southwestern most county in the United States.