An elliptical path is the oval-shaped orbit an object follows around a central body under gravity, with the central body sitting at one of the ellipse's two foci. Because the distance varies, the orbiting object speeds up when it's close and slows down when it's far.
An elliptical path is the trajectory an orbiting object traces out when gravity pulls it around a central body. Instead of a perfect circle, the orbit is an oval (an ellipse) with two focal points, and the central body (like the Sun) sits at one focus, not at the center. This is exactly what Kepler's First Law says about planetary orbits.
The key feature you care about in physics is that the distance between the two objects changes along the path. When the orbiting object is closest to the central body, gravity is stronger and the object moves fastest. When it swings out to its farthest point, gravity is weaker and it slows down. The whole motion stays consistent with conservation of angular momentum, which is why the object sweeps out equal areas in equal times (Kepler's Second Law).
Elliptical paths show up in Topic 12.3, Orbital Motion and Kepler's Laws. This is where you connect Newton's law of universal gravitation to the actual shapes of orbits. Kepler observed that planets follow ellipses, and Newton later proved those ellipses are a direct consequence of an inverse-square gravitational force.
Understanding the elliptical shape is what lets you reason about why orbital speed isn't constant, how to apply conservation of energy and angular momentum to an orbit, and how the same rules govern moons, comets, and artificial satellites. It's the bridge between abstract gravitational force equations and the real motion of celestial bodies.
Keep studying Principles of Physics I Unit 12
Visual cheatsheet
view galleryKepler's First Law (Unit 12)
Kepler's First Law is the statement that planetary orbits are ellipses with the Sun at one focus. The elliptical path is literally the geometry that law describes, so you can't separate the two.
Eccentricity (Unit 12)
Eccentricity measures how stretched out the ellipse is. A near-zero eccentricity gives an almost circular path, while a high eccentricity gives a long, skinny orbit like a comet's, so it tells you the shape of any given elliptical path.
Gravitational Force (Unit 12)
Gravity is what bends the object's straight-line motion into a closed elliptical path. Because gravity follows an inverse-square law, the force changes strength along the orbit, which is what makes the object speed up and slow down.
Periapsis (Unit 12)
Periapsis is the closest point of the orbit to the central body. It's where an object on an elliptical path moves fastest and feels the strongest gravitational pull.
Expect this on problem sets and exams in your orbital motion unit. You'll likely identify where the central body sits (at a focus, not the center), explain why orbital speed changes along the path, and apply conservation of energy and angular momentum to compare two points on the orbit. A common problem gives you speed and distance at periapsis and asks for them at the farthest point, which you solve using equal-area reasoning or conservation laws. You may also be asked to connect the elliptical shape directly to Kepler's First Law and to Newton's gravitational force.
A circular orbit is a special case where the distance stays constant, so speed and gravitational force never change. An elliptical path is the general case: distance, speed, and force all vary, and a circle is just an ellipse with zero eccentricity.
An elliptical path is an oval orbit with the central body located at one of the two foci, not at the center.
Because the distance changes along the orbit, the object moves fastest at its closest point and slowest at its farthest point.
Kepler's First Law states that planets follow elliptical paths, and Newton showed this comes directly from inverse-square gravity.
Equal areas are swept out in equal times, which is conservation of angular momentum in action.
A circle is just an ellipse with zero eccentricity, so circular orbits are a special case of elliptical paths.
It's the oval-shaped orbit an object follows around a central body under the pull of gravity. The central body sits at one of the ellipse's two foci, and the orbiting object's distance and speed change as it moves around.
Because its distance from the central body changes. When it's closest (periapsis), gravity is stronger and it speeds up; when it's farthest, gravity is weaker and it slows down, all while conserving angular momentum.
No. A circular orbit keeps a constant distance and constant speed, while an elliptical path has varying distance and speed. A circle is actually a special elliptical path with an eccentricity of zero.
At one of the two foci of the ellipse, not at the geometric center. This is exactly what Kepler's First Law describes for planets orbiting the Sun.
Yes. All bodies bound by gravity follow elliptical paths, though comets often have highly eccentric (very stretched) orbits while planets like Earth have nearly circular ones with low eccentricity.