**Three-body problem**

In classical mechanics, the three-body problem is to take the initial positions and momenta of three-point masses that revolve each other in space and analyze their trajectories or direction of movement using Newton’s law of universal gravitation and Newton’s laws of motion. However, there is no general solution to the three-body problem since the motion of the objects becomes chaotic. Unlike the two-body problem, which is easily described by Newton’s universal laws of gravitation**,** the solution to the three-body problem seems almost impossible since predicting the movement of such objects is complex, which means there is no equation that effectively solves this problem.

Since, there are no effective equations to solve most three-body systems, the approach to predict the motions of bodies is approximation them utilizing numerical methods. For instance, the movement of the Moon around Earth is influenced and disturbed by the gravitational force of the sun and one planet around the sun, along with being disturbed by the action of other planets**. **In unusual cases, this can be solved by overlooking the object, which is infinitely small, through the means of Lagrange points in which three bodies form an equilateral triangle. However, most three-body systems are chaotic; hence, it remains one of the complex problems that still does not have any perfect solution.

**What is Classical Mechanics? **

Classical Mechanics is the study of the motion of bodies under the influence of physical forces or with the equilibrium of objects when all forces are balanced. The laws of physics that govern by certain rules like force, mass and motion of an object. Classical Mechanics are conventionally segmented into three main branches. One isstatics**,** which helps in evaluating force and torque acting on physical systems that do not experience acceleration but rather are in equilibrium with respect to their surroundings. Besides, the study, which is mentioned as the geometry of motion, has provided an understanding of kinematics, which indicates the motion of systems and objects without consideration of their correlated physical properties along with forces acting on them.

Dynamics is another branch of physics that analyse the influences on the motion of objects. The four main principles of dynamics are energy, mass, momentum and force. Classical mechanics can be mathematically presented in various ways, and the physical content of these different formulations is identified to be the same; however, they provide different insights besides enabling various sorts of calculations. The Newtonian Mechanics is sometimes used as a substitute for non-relativistic classical physics**. **Thisisoftenreferred to formulation based on Newton’s laws of motion.

Newton also provided the first precise mathematical and scientific formulation of gravity in “Newton’s law of universal gravitation, and hence, the amalgamation of Newton’s laws of motion along with gravity provides a precise description of classical mechanics. He also demonstrated that the classical laws of physics apply to every object and celestial objects, which strengthens the theoretical clarification **of **Kepler’s laws of motion of the planets.

**Kepler’s laws of planetary motion **

Kepler’s laws of planetary motionin astronomy resolute the motions of planets in the solar system. Kepler derived three laws of motion, and the first law of his indicates that all planets revolve around the sun in elliptical orbits that are located at a focus of the ellipse. On the other hand, Kepler’s second law of planetary motion indicates that the imaginary line that joins a planet and the sun arches equal areas of space during equal time intervals as the planet revolves.

Besides that, Kepler’s third law indicates that the squares of the orbit periods of planets are directly proportional to the cubes of the semi-major axis of their orbits. These laws also indicate that the period of a planet to orbit the sun increases with the radius of its orbit.

The equation for Kepler’s Third Law is P^{2}=a^{3,} where P indicates a period of a planet’s orbit squared equal to the size of the semi-major axis of the orbit. Kepler’s laws extended to the motions of artificial satellites and extrasolar planets. The general problem of precisely predicting the motions of more than two bodies under their mutual attractions turns out to be very complicated, and analytical solutions to the three-body problem are unattainable apart from some special cases.

**Celestial Mechanics of Isaac Newton**

Sir Isaac Newton introduced the idea about the motion of objects such as the Sun, Moon and Planets of our solar system, and hence, it led to the establishment of a new method of science, which is widely known as Newton’s Theory of Universal gravitation. The foundation of Newton’s Theory of universal gravitation ascended from the perception that the force keeping the Moon in orbit around the Earth is the same that the Earth and other planets orbit around the sun.

**Newton’s Law of Universal Gravitation**

Newton’s law of Universal Gravitation allowed Newton to critically explain the motion of celestial objects**.** This strengthens the understanding of the universality of gravity. This Theory suggests that bodies attract themselves mutually with a force proportional to their masses and inversely proportional to the square of the distance between them.

Newton highlights that if two bodies have masses m1, m2 have a distance between them is r than the force between them, signified by F= G m1 *m2/ r^2. In this equation, the gravitational constant is (G=6.678 × 10^ ^{-8 }cm^3 g^{-1 }s^{-2}). This is a universal constant that does not rely on the nature of the objects and remains applicable in the rest of the universe. The law of universal gravitation examines the problem of the motion of two bodies in mutual attraction, which helps in the effective prediction of the movement of bodies that orbit around each other.

**FAQ**

**1. What is Classical Mechanics?**

Classical mechanics can be mathematically presented in various ways, and the physical content of these different formulations is identified to be the same; however, they provide different insights besides enabling various sorts of calculations. It also highlights the motion of bodies under the influence of physical forces or with the equilibrium of objects when all forces are balanced. The laws of physics that govern by certain rules like force, mass and motion of an object.

**2. What is Newton’s Law of Universal Gravitation and the two-body problem?**

Newton highlights that if two bodies have masses m1, m2 have a distance between them is r than the force between them, signified by F= G m1 *m2/ r^2. In this equation, the gravitational constant is (G=6.678 × 10^ ^{-8 }cm^3 g^{-1 }s^{-2}). The law of universal gravitation examines the problem of the motion of two bodies in mutual attraction, which helps in the effective prediction of the movement of bodies that orbit around each other.

**3. What is the body problem, and why is it unsolvable? **

Unlike the two-body problem, which is easily described by Newton’s universal laws of gravitation**,** the solution to the three-body problem seems almost impossible since predicting the movement of such objects is complex, which means there is no equation that effectively solves this problem. Since, there are no effective equations to solve most three-body systems, the approach to predict the motions of bodies is approximation them utilizing numerical methods.