The nautical mile and astronomical navigation: In navigation and aviation, especially at sea, the nautical mile is used as a unit of measurement. It is equivalent to one minute of angle along a meridian on Earth.

The nautical mile and astronomical navigation:

They define it as one minute of arc measured along any meridian.

In terms of distance, a nautical mile is equal to 1,852 kilometer.

People commonly use it to measure distances at sea or in the air.

The use of NM, the internationally agreed-upon measure of one nautical mile, which is exactly 1.852 meters, remains in place today

The nautical mile and astronomical navigation:

#### The nautical mile and astronomical navigation

In fact, envisioning the Earth halved simplifies the calculation since the NM derives from Earth’s circumference. (40.000 km)

After dividing the half-circle into equal portions of 360°, one can further divide these degrees into 60 minutes.

##### Classic explanation

Within navigation, one of these minutes (also referred to as minutes of arc) along a great circle on Earth represents a single NM.

overall, nautical charts employ one of three map projections: the gnomic, polyconic, and Mercator.

Among these three, the Mercator projection takes precedence as lines of latitude and longitude intersect at right angles, creating a rectangular grid.

In fact, this grid enables users to plot straight lines of latitude and longitude as direct courses easily for navigation purposes.

The nautical mile and astronomical navigation:

On this website, we explore creating a simplified plotting sheet inspired by the Mercator concept

Indeed, incorporating the NM, which represents one minute of latitude, greatly simplifies navigation in open water.

Consequently, it assumes a vital role in exploration, shipping, and geography, contributing significantly to these fields.

Difference between a nautical mile and a knot. NOAA