# What is an Ellipse Shape?

An ellipse has no edges, but it’s not a circle. More oval than a circle, but yet it’s not an oval. Read on to find out what an ellipse shape is.

What is an Ellipse Shape?

It was a Greek mathematician, Menaechmus, who first discovered the ellipse shape in 300BC. However, it wasn’t until around 100BC that Apollonius gave the ellipse shape its name in his infamous book ‘Conics.’

An ellipse is a shape that has two focal points, known as foci. These foci don’t ever move from where they are. And there’s a third point, which is away from the foci. Imagine a piece of string joining all three points to form a triangle.

Next, get a pencil to stand on the third point. This means it’s in one of the triangle’s three corners that the string has made.

Then move the pencil around the outside of the foci, yet still within the string. When the pencil returns to its original position, you have formed an ellipse shape.

The ellipse shape is an interesting one that, at first glance, could be confused for being a circle or even an oval. But it’s distinct in its own right, and we’ll explain why. We first need to look at the process and oval to do this.

What’s the difference between a circle and an ellipse?

A circle is a flat two-dimensional (2D) shape that’s curved and flat. All the points on a process are of equal distance to its center, like in the diagram below.

Although an ellipse is also a 2D shape that’s curved and flat, it doesn’t have all points that meet the center being of equal distance. Instead, the way it’s shaped means that when you add the length of the foci, they’re always the same.

Although both shapes can be different sizes, the ellipse shape can vary from very oval to very round. However, if both foci are in the same place in an ellipse, it’s no longer an ellipse but a circle.

What’s the difference between an oval and an ellipse?

All ellipse shapes are ovals, but interestingly enough, not all are ellipses. This is because when an ellipse’s size is fixed, the line that forms its perimeter cannot be changed. This means it can only be drawn one way, whereas an oval’s perimeter only has to be a concave curve and doesn’t have a fixed size.

What’s the Ellipse Shape used for?

• Ellipses are used a lot in physics and engineering.
• The shapes of boat keels, rudders, and even plane wings are often ellipse shapes.
• When it comes to astronomy, the ellipse shape is essential. This is because celestial objects periodically orbit around other celestial objects, and they all trace out ellipse shapes when doing this.
• Planets orbiting the sun make an ellipse shape when traveling around it, with the sun at one focus point.
• Ellipses also represent comets, satellites, and moons.
• We even cut food in a way that forms an ellipse shape. For example, consider how you cut a carrot or cucumber into slices; many of us miss it at an angle or it ends up cutting it that way, and when we do, that’s an ellipse.
• Elliptical trainers also mimic the ellipse shape in the motion it makes when simulating running or walking. Using this exercise machine, your foot forms an elliptical path through its movement.