Continuation…
Dr. Shanker Adawal
The Universe
Earth
The Earth is part of the Solar System; it is the third planet in order of its distance from the central body – the Sun. The Sun is an ordinary star, not something exceptional in the Universe. Together with the planets and other bodies of the Solar System, the Sun is a member of a huge stellar island known as a Galaxy. Our Galaxy is called the Milky Way. Galaxies are fundamental building-blocks of the Universe. They form groups and clusters of galaxies comprising tens and hundreds of members. Our Galaxy is part of the so-called Local Group of galaxies, which has some 25 members.
Let us now take a closer look at the above hierarchy and take note of the general features and evolutionary aspects;
The Solar System
The Solar System is our home in the Universe and we know it in some detail. Besides the Sun and other known planets, it includes countless other inhabitants, whose total mass is very much smaller than the mass of the central star. Seven planets are circled by various natural satellites or moons (almost 50 identified as of 1984). Besides these known planets, the Sun is surrounded by thousands of minor planets, or asteroids, moving mostly between the orbits of Mars and Jupiter. The orbits of the planets and most minor planets are located in planes not too inclined to the plane of the Earth’s orbit, and that is why we observe the given objects in the sky near the ecliptic, moving `through’ the 12 zodiacal constellations.
The orbits of another group of objects, the comets, are quite different. Some extend from beyond the orbit of the planet Pluto in closer to the Sun than the Earth ever gets. Meteor streams formed by the disintegration of comets, collections of cosmic junk orbiting the Sun together, have similar orbits. The movements of all members of the Solar System are governed by the law of gravity, which applies throughout the Universe.
The star called the Sun, on the one hand, and the planets, on the other, represent two essentially different types of cosmic bodies, differing primarily in mass. Stars are gaseous bodies which are self-luminous, as a result of nuclear processes in the stellar interior. Stars may differ markedly in size; some are much smaller than the Sun, but there are also other, giant stars, with a diameter greater than the orbit of the planet Mars. Their masses, however, are always within the fairly small range of 1032 g to 1035 g. A body with a mass of less than some 1032 g does not have sufficient heat in its interior to initiate a nuclear reaction.
1. The object known as `Chiron’, between the planets Saturn and Uranus, is not a planet but a much smaller object, an asteroid.
2. 1032 is shorthand for 1 followed by 32 Zeros, or one hundred million billion billion.
Planets are bodies of smaller mass than stars and are not self-luminous. They are cold on the surface and shine only by reflected light.
The planets in our Solar System are divided according to their distance from the Sun into two groups – the inferior planets (Mercury and Venus) and the superior planets (from Mars outward).
They are furthermore differentiated according to their physical and chemical properties into terrestrial planets and so-called major planets. The first include Mercury, Venus, Earth, Mars, and in all probability also Pluto. They resemble one another not only by having smaller dimensions than the major planets but also in chemical composition, mass and solid surface with similar morphological features. Common surface formations on terrestrial planets (and on their moons) are the ring-like walled enclosures called craters. Craters testify to strong bombardment by meteoritic bodies in the early phase of the evolution of the planets and their satellites. Besides impact craters (caused by the impact of meteoritic bodies) there are also craters and many other formations of volcanic or tectonic origin. The external appearance of some planets (Earth, Venus, Mars) has also been influenced in great degree by the effects of atmosphere and/or water.
Continue…
Shanker Adawal
Profile: www.connectingmind.com
Research work and articles on Bhrigu Nadi astrology: www.shankerstudy.com
www.shankarsastro.com
Published articles on Articlesbase.com
http://www.articlesbase.com/authors/shanker-adawal/149926
or search keyword "shanker adawal" in google search for published articles
Join my Facebook Group for free Astro Queries: www.facebook.com/adawal
Published articles on Newspapers: http://tinyurl.com/2wyxtfk
Year 2012 for you: http://tinyurl.com/2012foryou
No comments:
Post a Comment
Thanks for your interest in my blog post.