02 Solar System1

The Solar System HARSHA SINVHAL AND M. ISRAILDEPARTMENT OF EARTH SCIENCESI.I.T. ROORKEEDisclaimer: These notes are for personal use only. If any error of omission is found the same may be reported to the authors for necessary corrections.

*GP_1_Solar System.ppt

GP_1_Solar System.ppt

*GP_1_Solar System.pptThe Solar System The Solar System consists of the Sun and the other celestial objects gravitationally bound to it.

In addition to the Sun it has four terrestrial inner planets,an asteroid belt composed of small rocky bodies, four gas giant outer planets, a second belt, called the Kuiper belt, composed of icy objects.


*GP_1_Solar System.pptObjects orbiting the Sun are divided into three classes: Planets, Dwarf planets, and Small Solar System Bodies (SSSBs).PLANETS:


*GP_1_Solar System.pptA planet is any body in orbit around the Sun that a) has enough mass to form itself into a spherical shape and b) has cleared its immediate neighbour-hood of all smaller objects. There are eight known planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.On August 24, 2006 the International Astronomical Union defined the term planet for the first time, excluding Pluto and reclassifying it under the new category of dwarf planet along with Eris and Ceres.

PLANETS:Contd..


*GP_1_Solar System.pptThe eight planets have their 165 known moons, Natural satellites, or moons, are those objects in orbit around planets, dwarf planets and SSSBs, rather than the Sun itself.In addition to this there are billions of small bodies within our solar system. This last category includes asteroids, Kuiper belt objects, comets, meteoroids and interplanetary dust. PLANETS:Contd


*GP_1_Solar System.pptIn order of their distances from the Sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Six of the eight planets are in turn orbited by natural satellites, usually termed "moons" after Earth's Moon,

Each of the outer planets is encircled by planetary rings of dust and other particles.

All the planets except Earth are named after gods and goddesses from Greco-Roman mythology. PLANETS:Contd


*GP_1_Solar System.pptA dwarf planet is not required to clear its neighbourhood of other celestial bodies. Other objects that may become classified as dwarf planets are Sedna, Orcus and Quaoar.There are three currently identified dwarf planets (including Pluto). The three dwarf planets are Pluto, the largest known Kuiper belt object; Ceres, the largest object in the asteroid belt; and Eris, which lies in the scattered disc.The remainder of the objects in orbit around the Sun are Small Solar System Bodies (SSSBs).DWARF PLANETS:


*GP_1_Solar System.pptA planet's distance from the Sun varies in the course of its year. Its closest approach to the Sun is called its perihelion, while its farthest distance from the Sun is called its aphelion.Perihelion - Aphelion


*GP_1_Solar System.pptAstronomers usually measure distances within the Solar System in astronomical units (AU). One AU is the approximate distance between the Earth and the Sun, or roughly 149,598,000km (93,000,000 mi). Pluto is roughly 38 AU from the Sun while Jupiter lies at roughly 5.2 AU. One light year, the best known unit of interstellar distance, is roughly 63,240 AU.Astronomical Unit (AU)


*GP_1_Solar System.ppt[edit] Layout and structure

The principal component of the Solar System is the Sun, that contains 99.86% of the system's known mass and dominates it gravitationally.

Jupiter and Saturn, the Sun's two largest orbiting bodies, account for more than 90% of the system's remaining mass

Mass Distribution in the Solar System


*GP_1_Solar System.pptObjects travel around the Sun following Keplers laws of planetary motion. Each object orbits along an approximate ellipse with the Sun at one focus of the ellipse. The closer an object is to the Sun, the faster it moves. The orbits of the planets are nearly circular, but many comets, asteroids and objects of the Kuiper belt follow highly-elliptical orbits.Keplers Law of Planetary Motion


*GP_1_Solar System.pptTo cope with the vast distances involved, many representations of the Solar System show orbits the same distance apart. In reality, with a few exceptions, the farther a planet or belt is from the Sun, the larger the distance between it and the previous orbit. For example, Venus is approximately 0.33 AU farther out than Mercury, while Saturn is 4.3 AU out from Jupiter, and Neptune lies 10.5 AU out from Uranus. Attempts have been made to determine a correlation between these orbital distances (Titius_Bode Law), but no such theory has been accepted.Titius-Bode Law for Inter-planetary Distances


*GP_1_Solar System.pptThe law relates the semi-major axis a of each planet outward from the Sun in units such that the Earth's semi-major axis is equal to 10:a = 4 + nwhere n = 0, 3, 6, 12, 24, 48 , each value of n > 3 twice the previous value. The resulting values can be divided by 10 to convert them into astronomical units (AU), which would result in the expressiona = 0.4 + 0.3 2mfor m = -, 0, 1, 2 For the outer planets, each planet is predicted to be roughly twice as far from the Sun as the previous object.TitiusBode law


*GP_1_Solar System.ppt1 ( dwarf planets)

PlanetkT-B rule distance (AU)Real distance (AU)% error (using real distance as the accepted value)Mercury00.40.392.56%Venus10.70.722.78%Earth21.01.000.00%Mars41.61.525.26%Ceres182.82.771.08%Jupiter165.25.200.00%Saturn3210.09.544.82%Uranus6419.619.22.08%Neptune12838.830.0629.08%Pluto125677.2239.4495.75%


*GP_1_Solar System.pptMost large objects in orbit around the Sun lie near the plane of Earth's orbit, known as the ecliptic. The planets are very close to the ecliptic while comets and Kuiper belt objects are usually at significantly greater angles to it.All of the planets and most other objects also orbit with the Sun's rotation in a counter-clockwise direction as viewed from a point above the Sun's north pole. There are exceptions, such as Halleys Comet.Plane of Orbit of Planets


*GP_1_Solar System.pptThe planets can be divided into two distinct categories on the basis of their densities.

The inner, or terrestrial, planets Mercury, Venus, Earth and Mars have rocky compositions and densities greater than 3 grams per cubic centimeter (g/cm3)

In contrast, the outer, or Jovian, planets- Jupiter, Saturn, Uranus and Neptune-are large objects with densities less than 2g/cm3 and thus are composed primarily of gas.Density of Planets:


*GP_1_Solar System.pptThe current paradigm for solar system origin suggests that its formation began with the collapse of part of an interstellar cloud of gas and dust, with an initial mass only 10 to 20 percent larger than the present mass of the Sun. This collapse could be initiated by random fluctuations of density within the cloud, one or more of which might result in the accumulation of enough material of cause the cloud to collapse. The initial cloud would have to be roughly spherical in shape.ORIGIN OF SOLAR SYSTEM:


*GP_1_Solar System.pptBecause it is revolving around the centre of the galaxy, the outer edge of the cloud (i.e., the one farthest from the galactic centre) moves more slowly than the inner part.

Hence the collapse of the cloud would cause it to rotate and in order to conserve angular momentum the speed of rotation would increase as the cloud contracts. As the contraction continues, the cloud flattens, as it is easier for matter to follow the attraction of gravity along the axis of rotation than perpendicular to it, where the opposing centrifugal force is greatest.

ORIGIN OF SOLAR SYSTEM: Contd.


*GP_1_Solar System.pptThus a flattened disk is formed around a central condensation (as in the model of Laplace). This configuration, commonly referred to as the solar nebula, would resemble the shape of a typical spiral galaxy on an enormously reduced scale. As gas and dust are pulled in toward the central condensation, their potential energy is converted to kinetic energy and the temperature of the material rises.

Ultimately the temperature becomes great enough in the interior of the condensation for nuclear reactions to begin, thereby giving birth to a star.ORIGIN OF SOLAR SYSTEM: Contd.


*GP_1_Solar System.ppt Light speed of 300 000 000 m/s.

How long does light from the Sun take to reach Earth? (distance of Earth from the Sun is 150 million km)

= 500 seconds (/60 =8.3 minutes)TIME ESTIMATION


*GP_1_Solar System.pptIf you were in a spaceship that travelled at the speed of light and you started a journey from the Sun it would take approximately:

3 minutes to reach Mercury,

5 minutes to reach Venus,

8 minutes to reach the Earth,

51/2 hours to reach Pluto,4 years to reach the next star,5000 years to reach the edge of the galaxy,50 000 years to reach the next galaxy,500 000 years to reach the next Cluster!!TIME ESTIMATION


*GP_1_Solar System.ppt The next star nearest to Earth (after the sun) is called Proxima Centauri and is 4.22 light yearsaway.


*GP_1_Solar System.pptTHE SEASONS IN THE NORTHERN HEMISPHERE


*GP_1_Solar System.pptTHE SEASONS IN THE SOUTHERN HEMISPHERE


*GP_1_Solar System.pptTHANK YOU


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02 Solar System1

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