Earth’s Orbit Around The Sun. Diagram of the Earths orbit around the Sun. Credit: NASA/H. Zell Ever since the 16th century when Nicolaus Copernicus demonstrated that the Earth revolved around in the Sun, scientists have worked tirelessly to understand the relationship in mathematical terms. If this bright celestial body – upon which depends the seasons, the diurnal cycle, and all life on Earth – does not revolve around us, then what exactly is the nature of our orbit around it? For several centuries, astronomers have applied the scientific method to answer this question, and have determined that the Earth’s orbit around the Sun has many fascinating characteristics.
First of all, the speed of the Earth’s orbit around the Sun is 108,000 km/h, which means that our planet travels 940 million km during a single orbit. The planet’s distance from the Sun also varies as it orbits. The average distance of the Earth from the aun is about 149.6 million km, which is also referred to as one astronomical unit (AU). Related Mars. Newtonian Gravitation and the Laws of Kepler.
Newtonian Gravitation and theLaws of Kepler We now come to the great synthesis of dynamics and astronomy accomplished by Newton: the Laws of Kepler for planetary motion may be derived from Newton's Law of Gravitation. Furthermore, Newton's Laws provide corrections to Kepler's Laws that turn out to be observable, and Newton's Law of Gravitation will be found to describe the motions of all objects in the heavens, not just the planets. Acceleration in Keplerian Orbits Kepler's Laws are illustrated in the adjacent animation.
Notice that (because of Kepler's 2nd Law) the velocity vector is constantly changing both its magnitude and its direction as it moves around the elliptical orbit (if the orbit were circular, the magnitude of the velocity would remain constant but the direction would change continuously). Newton's Laws and Kepler's Laws Conic Sections and Gravitational Orbits The ellipse is not the only possible orbit in a gravitational field. Examples of Gravitational Orbits. Perihelion, Aphelion and the Solstices. The Earth is closest to the Sun or at its Perihelion two weeks after the December solstice and farthest from the Sun or Aphelion, two weeks after the June Solstice. In 2015, the Earth will reach its Aphelion at 19:41 (7:41 pm) UTC on July 6, 2015. This is 15 days after the June Solstice. The Earth reached its Perihelion at 6:37 am UTC on January 4, 2015, 14 days after the 2014 December Solstice.
Aphelion event in your local time Elliptical orbit Many people believe that the Earth moves around the Sun in a circular path. But this is not true. The shape of this path varies due to gravitation influences of other planetary objects. Earth's Perihelion and Aphelion The Earth is closest to the sun, or at the Perihelion, about two weeks after the December solstice, when it is winter in the Northern Hemisphere.
The Earth is about 91,402,500 miles (147,098,070 kilometers) from the Sun, when it is at its Perihelion, and about 94,509,100 miles (152,097,700 kilometers), when it is at the Aphelion point. Kepler's Three Laws. In the early 1600s, Johannes Kepler proposed three laws of planetary motion. Kepler was able to summarize the carefully collected data of his mentor - Tycho Brahe - with three statements that described the motion of planets in a sun-centered solar system. Kepler's efforts to explain the underlying reasons for such motions are no longer accepted; nonetheless, the actual laws themselves are still considered an accurate description of the motion of any planet and any satellite.
Kepler's three laws of planetary motion can be described as follows: The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. The Law of Ellipses Kepler's first law - sometimes referred to as the law of ellipses - explains that planets are orbiting the sun in a path described as an ellipse. Constructed using a pencil, two tacks, a string, a sheet of paper and a piece of cardboard. The Law of Equal Areas The Law of Harmonies k = 2.97 x 10-19 s2/m3 = (T2)/(R3) 1. GCSE Bitesize: The solar system. History and Philosophy of Western Astronomy.
Chapter index in this window — — Chapter index in separate window This material (including images) is copyrighted!. See my copyright notice for fair use practices. Select the photographs to display the original source in another window. Johaness Kepler (lived 1571--1630 C.E.) was hired by Tycho Brahe to work out the mathematical details of Tycho's version of the geocentric universe. Kepler was a religious individualist. Since an infinite number of models are possible (see Plato's Instrumentalism above), he had to choose one as a starting point. Kepler tried to refine Copernicus' model. An ellipse is a squashed circle that can be drawn by punching two thumb tacks into some paper, looping a string around the tacks, stretching the string with a pencil, and moving the pencil around the tacks while keeping the string taut.
There are some terms I will use frequently in the rest of this book that are used in discussing any sort of orbit. Select the image to show an animation of Kepler's 3 laws. History and Philosophy of Western Astronomy. The Solar System | S-cool, the revision website. The Solar System is made up of the nine planets, including the Earth, that orbit (go round) the Sun. See whether you can name them on the diagram below: The four inner planets are called terrestrial planets and are small rocky planets.
Between Mars and Jupiter, there is an asteroid belt, which may be the remains of a planet. The next four are called gas giants and are large planets made up of gas. Pluto is a very cold lump of rock, with a moon - Charon - nearly as large as Pluto. Decide whether the following facts are true or false: The moon orbits the earth in 28 days and the Earth orbits the sun in 365¼ days. As mentioned above, the planets move in near circular orbits called ellipses. Objects will only move in a circle if there is a force acting on them. But why must there be a force for objects to travel in a circle?
Speed and velocity Velocity is speed with direction. Below is a brief demonstration to show this. We call the force that keeps things moving in a circle a centripetal force. 1. GCSE Science: GCSE Physics - our solar system. Our Solar System consists of the Sun with planets in orbit around it. Most planets have at least one satellite (moon) in orbit around them. Gravity provides the centripetal force needed to keep objects in orbit. We can explore space using manned or unmanned spacecraft. Our solar system consists of: a star (the Sun) planets and dwarf planets in orbit around the Sun satellites (moons) in orbit around most of the planets comets and asteroids in orbit around the Sun The Earth is just one of the eight major planets orbiting the Sun.
There are also dwarf planets, such as Eris, Pluto, and Ceres. The Sun's gravity keeps the planets, dwarf planets, comets and asteroids in orbit. The Sun Our Sun is just one of at least 200 billion stars in our galaxy, the Milky Way. A galaxy is large group of many millions of stars. Planets The time for a planet to do a single orbit (i.e. to go round the Sun once) is called the planet's year.
My Very Elegant Mother Just Served Us Nine Peas Dwarf planets. GCSE SCIENCE PHYSICS HIGH SCHOOL - The Planets - Orbit and Gravity - gcsescience.com. GCSE Bitesize: The solar system.