Meridian

Definition

A meridian is an imaginary line that runs from the North Pole to the South Pole and passes through a specific point on Earth's surface. It is used in astronomy to determine the position of celestial bodies.

5 Must Know Facts For Your Next Test

1. The Prime Meridian, located at 0° longitude, is the starting point for measuring longitude.
2. Meridians are essential in celestial navigation and timekeeping.
3. The local meridian of a location is used to determine when a celestial object will be at its highest point in the sky.
4. Every place on Earth has its own local meridian.
5. When a celestial object crosses an observer's local meridian, it reaches its highest altitude above the horizon, known as culmination.

Review Questions

• What is the significance of the Prime Meridian?
• How do meridians assist in determining the position of celestial bodies?
• What happens when a celestial object crosses an observer's local meridian?

Related terms

Longitude: A geographic coordinate that specifies the east-west position of a point on Earth's surface.

Culmination: The moment when a celestial object reaches its highest point in the sky as seen by an observer.

Celestial Sphere: An imaginary sphere surrounding Earth onto which all celestial objects can be projected for positional reference.