Final answer:
A North-South line intersecting the baseline on Earth is a meridian or a line of longitude, crucial for geographic orientation. It, along with parallels or lines of latitude, forms the geographic coordinate system used for navigation and mapping.
Step-by-step explanation:
An imaginary line that runs in a North-South direction and intersects with the base line on Earth is known as a meridian or a line of longitude. These lines are crucial for geographical orientation and help in determining the precise location of a place on the planet. Unlike lines of latitude that are parallel to the equator, meridians converge at the poles and are furthest apart at the equator. Meridians and parallels together form a grid that is used for navigation and mapping, known as the geographic coordinate system.
The meridian that is designated as the starting point for measuring longitude is the Prime Meridian, which passes through Greenwich, England. Locations east of the Prime Meridian are considered to have positive longitude, while locations west have negative longitude. As an imaginary line, a meridian is conceptual and aids in the division of Earth into the Eastern and Western Hemispheres.
Geographers and cartographers use another set of imaginary lines, called the equator and latitude lines, in conjunction with meridians to locate any point on Earth. The concept is similar to a Cartesian coordinate system in mathematics, where the origin is the reference point, but adapted to the spherical nature of the Earth. When considering the globe as a whole, one could say that the Earth's axis serves as a natural north-south line, around which Earth rotates.