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A sphere is a space figure that is perfectly round. All points on the surface of a sphere are at an equal distance from its center. The center is shown with a red dot in the figure below.

- A soccer ball

- A marble

- A basketball

- An orange

- Water droplets
- Earth

Is a sphere flat or curved?

A sphere is curved, not flat. Our perception that it is flat is influenced by the fact that we cannot see the Earth from a great distance. Satellite imagery captured by satellites have confirmed that the Earth is indeed curved or round.

Is the Earth a perfect sphere?

The Earth is called a sphere because it resembles very much a sphere. However, strictly speaking the Earth is not a perfect sphere.

In fact, real-world objects such as the Earth, a soccer ball, a marble will never be perfect spheres because they will have irregularities and imperfections here and there.

What is the difference between a sphere and a perfect sphere?

Basically, a sphere is the same as a perfect sphere. However, it is not easy to find objects in real-life that can be called perfect spheres. The term "sphere" has therefore expanded to define not only a perfect sphere, but also anything looking like a sphere. The term "perfect sphere" is just a mathematical concept.