Which of the following is Prime Meridian?
0° longitude
Understanding the Prime Meridian in Geography
The Earth's surface is crisscrossed by a grid of imaginary lines that help us locate places precisely. These lines are known as latitude and longitude. Lines of longitude, also called meridians, run from the North Pole to the South Pole.
Longitude is measured in degrees, minutes, and seconds, both east and west from a starting line. This starting line is a specific meridian that is designated as the reference point for all other longitudes. This reference meridian is known as the Prime Meridian.
Historically, different countries used different meridians as their prime meridian. However, at an international conference held in Washington, D.C., in 1884, it was agreed to establish a single, internationally recognized Prime Meridian. This meridian passes through the Royal Observatory in Greenwich, London, United Kingdom.
Therefore, the Prime Meridian is defined as the meridian at 0\degree longitude.
Meridians are measured eastward up to 180\degree E and westward up to 180\degree W. The 180\degree longitude line, roughly opposite the Prime Meridian, is significant as it is where the International Date Line is located.
Analyzing the Options
Let's look at the given options:
- 0\degree longitude: This is the internationally accepted definition of the Prime Meridian that passes through Greenwich.
- 180\degree longitude: This meridian is approximately where the International Date Line is located. It is directly opposite the Prime Meridian on the globe.
- 90\degree longitude: This refers to the meridian at 90\degree either East or West of the Prime Meridian. These are specific lines of longitude but not the Prime Meridian itself.
- 90\degree W longitude: This specifies the meridian located 90\degree west of the Prime Meridian. Again, a specific line of longitude, but not the Prime Meridian.
Based on the definition, the Prime Meridian is located at 0\degree longitude.
Revision Table: Important Geographic Lines
| Line | Description | Location |
|---|---|---|
| Prime Meridian | Starting line for measuring longitude | 0\degree Longitude (passing through Greenwich) |
| Equator | Starting line for measuring latitude | 0\degree Latitude |
| International Date Line | Roughly follows the 180\degree meridian; marks where a new calendar day begins | Approximately 180\degree Longitude |
| Tropic of Cancer | Northernmost latitude where the sun can be directly overhead | Approximately 23.5\degree N Latitude |
| Tropic of Capricorn | Southernmost latitude where the sun can be directly overhead | Approximately 23.5\degree S Latitude |
Additional Information on Geographic Coordinates
The system of latitude and longitude forms a grid system on the Earth's surface, allowing any location to be specified with a unique pair of coordinates (latitude, longitude). Latitude lines (parallels) run east-west and measure distance north or south of the Equator. Longitude lines (meridians) run north-south and measure distance east or west of the Prime Meridian.
The Prime Meridian is fundamental for global navigation and timekeeping. It is the reference point for measuring time zones around the world. Greenwich Mean Time (GMT), or Coordinated Universal Time (UTC) as it's now known, is the standard time at the Prime Meridian.
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