Lecture

Kepler Laws: Introduction to Astrophysics

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In course

PHYS-209: Astrophysics I: introduction to astrophysics

Ce cours décrit de façon simple les processus physiques qui expliquent l'univers dans lequel nous vivons. En couvrant une large gamme de sujets, le but du cours est aussi de donner un aperçu général des objets astrophysiques qui nous entourent. ...

Description

This lecture introduces the Kepler Laws, which describe the motion of planets around the Sun. The three laws state that planets move in elliptical orbits with the Sun at one focus, sweep out equal areas in equal times, and have orbital periods related to the semi-major axis. The concept of orbital planes and the law of areas are also discussed, emphasizing the relationship between the radius vector and the area swept by it. Furthermore, the lecture covers the concept of reduced mass and its application in the third Kepler Law, highlighting the relationship between the masses of celestial bodies and their distances. The lecture concludes by explaining that the orbital period of a planet is independent of its eccentricity.

In MOOC

Introduction to Astrophysics

How can we study the Universe we live in using the only available information it provides us with: light ? This course provides an overview of the physical phenomena at play in the astronomical objects surrounding us, from planets and stars to the cosmic filaments, from galaxies such as our own Milky Way to large galaxy clusters. The course emphasizes the links between theoretical predictions and observations. In this course, you will learn the basics of astrophysics using simplified mathematical developm

Official source

Ontological neighbourhood

Astronomy

Astrodynamics: Topics in astrodynamics

Related concepts (32)

Orbit

In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory.

Kepler's laws of planetary motion

In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler between 1609 and 1619, describe the orbits of planets around the Sun. The laws modified the heliocentric theory of Nicolaus Copernicus, replacing its circular orbits and epicycles with elliptical trajectories, and explaining how planetary velocities vary. The three laws state that: The orbit of a planet is an ellipse with the Sun at one of the two foci. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

Orbital period

The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, e.

Orbital elements

Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same orbit, but certain schemes, each consisting of a set of six parameters, are commonly used in astronomy and orbital mechanics. A real orbit and its elements change over time due to gravitational perturbations by other objects and the effects of general relativity.

Orbital mechanics

Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal gravitation. Orbital mechanics is a core discipline within space-mission design and control. Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity, including both spacecraft and natural astronomical bodies such as star systems, planets, moons, and comets.

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