Here's a breakdown:
* Ellipse: An ellipse is a closed curve where the sum of the distances from any point on the curve to two fixed points (called the foci) is constant.
* Sun: The sun is located at one focus of the ellipse.
* Orbit: The path of a planet around the sun is its orbit, and this orbit is an ellipse.
Why is it an ellipse and not a perfect circle?
This is due to the law of gravitation which states that:
* Every particle of matter in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
The planets' speeds aren't constant throughout their orbit due to the varying gravitational pull from the sun, leading to the elliptical shape.
Important Note: While most planets have relatively circular orbits, some are more elliptical. Pluto, for example, has a very eccentric (non-circular) orbit.
