A sphere.
A curved surface on which all points are the same distance from the center is called a sphere.
It is called the radius. The full distance is called the diameter.
The line that passes through the middle of a sphere or planet is called its diameter. The diameter is the longest distance across the sphere, passing through its center, and it is twice the length of the radius, which is the distance from the center to the surface.
That's a sphere.
A sphere.
A curved surface on which all points are the same distance from the center is called a sphere.
The distance from the surface of the Earth to its center is approximately 6,371 kilometers.
Surface of a sphere
The average distance from Earth's surface at the equator its center is about 6378 km. The distance from near the north and south poles to the center is somewhat less.
The term that indicates the distance between the surface at the center of a reflective surface and the focal point is called the "focal length." In optics, this distance is crucial for determining how light converges or diverges when it strikes the reflective surface. The focal length is a key parameter in the design of lenses and mirrors.
The distance from surface to surface through the center of a planet would be that planet's "diameter".
The distance between the surface at the center of a reflective surface and its focal point is equal to half the radius of curvature of the surface.
It is called the radius. The full distance is called the diameter.
7,000 km
That is called a sphere.
The distance from the Earth's surface to its center is approximately 3,963 miles.
A great circle is any circle on the surface of a sphere whose center is at the center of the sphere. The shortest distance between two points on the surface of a sphere is a part of the great circle that passes through them.