The "huge grid" that wraps the earth - the longitude and latitude coordinate system

I believe that most people in modern society use navigation in their daily lives.

After all, China is now making great progress in transportation construction. There are more and more roads, and the transportation network is becoming more and more complex. Without navigation, it would probably bring inconvenience to many people.

Of course, it is another matter for those who, even with a navigation system, have no idea when they will reach their destination. . .

Generally, when we use navigation, we directly enter an address to search, then find the end point and know the distance between the two places.

But ordinary people are just ordinary people. People like cartographers, pilots, geologists, and geographers are different from ordinary people.

They use a geographic coordinate system measured in longitude and latitude.

You heard it right. It's the longitude and latitude in the geography puzzle that tormented us in junior high and high school - calculating time based on longitude and latitude.

The main reason why they are different from us is the nature of their work. They need more precise and specific measurement methods, and using longitude and latitude to measure can accurately locate any location in the world.

This system of longitude and latitude starts with an imaginary grid of lines covering the entire planet, and is measured based on X (latitude) and Y (longitude) coordinates within the grid.

The longitude mentioned here refers to the imaginary line from the North Pole to the South Pole, also known as the meridian, of which there are 360.

The Prime Meridian (0 degrees longitude) passes through the Greenwich Observatory in the UK, also known as the International Date Line, and is the starting point of the world's standard "time zone".

Simply put, if your house happens to be built on this line, then walking around your house casually may mean the difference between today and tomorrow. It's quite exciting to think about it.

This latitude is the angle between the plumb line in the direction of gravity on the earth and the equatorial plane.

Latitudes are also called parallels because they run parallel to each other and to the equator.

The equator is the largest latitude circle with the center of the earth as the center, which divides the earth into the northern and southern hemispheres.

When all these longitude and latitude lines intersect, they form a "giant grid".

Through this "giant network", we can accurately locate the geographic location.

Since longitude is only 360 degrees (east-west longitude), latitude is only 180 degrees (north-south latitude).

In order to further accurately locate, the measured value is expressed not only in degrees, but also in minutes and seconds. #For example, Changsha = 28 ° 11′ 49 〃N, 112 ° 95′ 42 〃E

After understanding longitude and latitude, everyone must be curious about the distance between longitude and latitude, right?

Let’s talk about this now.

Because latitudes are parallel to each other, the distance between latitudes remains constant in most cases.

But as we all know, the Earth is elliptical, so there will be slight changes in the number from the equator to the North and South Poles.

Near the equator, the distance between latitudes is 110.567 kilometers, but within the Arctic and Antarctic Circles, the distance between latitudes is 111.699 kilometers.

However, each degree of latitude is approximately 111 kilometers apart.

For example.

If we are at 39 degrees north latitude and 116 degrees east longitude (near Tiananmen Square in Beijing).

Then we will go north to 40 degrees north latitude and 116 degrees east longitude, and we will drive 111 kilometers, and we will arrive near Sihedao Village, Baoshan Town, Beijing.

Longitude is different. The distance between longitudes can vary greatly depending on the latitude.

The distance between degrees of longitude is widest at the equator, at 111.321 km.

The closer you get to the poles, the distance will gradually decrease until the distance at the poles becomes zero.

For this kind of geographical content, everyone must have a picture in their mind. Imagine the earth model, and it will be easy to understand.

In addition, there are also calculations for distances between latitudes and longitudes. We can use the haversine formula to calculate the distance.

in:

● R is the radius of the earth, the average value can be 6371km

● φ1, φ2 represent the latitudes of two points;

● Δλ represents the difference in longitude between two points.

However, this formula is not something that ordinary people can calculate.

But fortunately, people invented computers, which made the problem much simpler. (Simplify the earth into a standard circle)

#This is the Haversine formula code, where lon1, 2 and lat1, 2 are two longitude and latitude points, and the distance between the two longitude and latitude points can be calculated.

# Input two longitude and latitude coordinates

#Enter the radius of the earth

Use the harversine formula to calculate the distance between two points on a sphere.

Of course, if you still find it troublesome, you can also directly use the latitude and longitude distance calculation tool to calculate the straight-line distance between two locations.