A horseshoe orbit is the type of orbit you get when you observe an object from another nearly co-orbital object, such as a planet. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... A planet (from the Greek πλανήτης, planētēs which means wanderer or more forcefully vagrant, tramp) is an object in orbit around a star that is not a star in its own right. ...

For example, if an object orbits the Sun in slightly less or more than a year, and if its orbit is a little more eccentric than Earth's, every year it will appear to trace a kidney-bean shape around a point on Earth's orbit. The loop is not closed but will drift forward or backward slightly each time, so that the point it circles will appear to move smoothly along Earth's orbit over a long period of time. When the object approaches Earth closely at either end of its multi-year trajectory, gravitational exchanges of energy and momentum conspire to reverse the object's apparent progress. As a result, over an entire cycle the loops will fill out a horseshoe shape, with the Earth in the horseshoe's gap. A sun is the star at the center of a solar system. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... (This page refers to eccitricity in astrodynamics. ...

Several asteroids (such as 3753 Cruithne and 2002 AA₂₉) are known to occupy horseshoe orbits with respect to Earth. The moons of Saturn Epimetheus and Janus occupy horseshoe orbits with respect to each other (in their case, there is no repeated looping: each one traces a full horseshoe with respect to the other). An asteroid is a small, solid object in our Solar System, orbiting the Sun. ... 3753 Cruithne is an asteroid in orbit around the Sun. ... Asteroid 2002 AA29 (also written 2002 AA29) is a near-Earth asteroid discovered in January 2001 by the LINEAR asteroid survey. ... Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Janus (jay-nus, Greek Ιανός) is a moon of Saturn. ...

--- The following normal orbit rules are needed to understand the creation of a horseshoe orbit.

1. If your orbit is slightly inside the orbit of the planet/moon, you orbit slightly faster than that planet/moon. If you started in front of the planet, you would slowly drift away because you're orbiting faster.

2. If your orbit is slightly outside the orbit of the planet/moon, you orbit slightly slower. If you started a bit behind the planet, you will slowly drift away because you're orbiting slower.

3. When you slow down in an orbit, you drop into a smaller orbit and the net result is smaller, faster orbit. This is VERY counter-intuitive, but it is the key to the whole thing.

4. When you speed up in an orbit, you rise to a higher orbit and the net result is a larger slower orbit.

So starting from the high orbit (slower). You fall behind the planet and drift away. But your still in almost the same orbit. So you eventually drift all the way around the orbit and find yourself approaching the planet from in front.

As you get closer, the planet's gravity starts pulling on you. This slows you down. But the slowdown isn't linear, it's circular! Slowing down means dropping into a lower orbit. This in turn means you start going around the Sun faster. So you start drifting away from the planet, because your moving faster.

Still with me? Here's the summary:

In a high orbit, your moving slower than the planet and you approach from the front, orbitally speaking. The planet slows you down, dropping you into a lower, faster orbit and you start pulling away again.

You race around the orbit and catchup to the planet from behind. Now the gravity increases your speed, pulls you into a higher, slower orbit and you start falling behind again.

If you observe this cycle from the earth, it looks like the asteroid moves slowly toward the earth over a period of years. Then it mysteriously starts moving toward or away from the sun. Finally it starts moving away from the earth, without ever going around the earth.

The cycle happens over the span of hundreds of actual orbits around the sun or other central body. But from the perspective of someone standing on the planet, it looks like your running in a horseshoe shaped orbit.