1. According to modern theories, our solar system was formed from a cloud of rarefied gasses, consisting from random clusters of hydrogen and cosmic dust. The Sun - the centre of our future solar system did not yet exist.
 
 

2. Gravitational forces gradually caused compression of the turning cloud. The density of the substance in its centre increases and takes the form of a disk.
 
 

3. As a result of compressive forces, the new-born Sun begins to radiate light energy.
 
 

4. On the periphery of the cloud, a gas/dust-like material also concentrates and forms local clusters.
 
 

5. Compression of the Sun and radiation of its energy proceeds. The number of local clusters in the solar cloud grows
 
 

6. Another large part of the solar cloud forms separate clusters of proto-planets.
 
 

7. The Sun, a star surrounded by proto-planets, is compressed down to its modern size; its brightness is about half of what it is today.
 
 

8. The temperature of an internal part of the Sun reaches critical mass, causing a thermonuclear reaction, converting Hydrogen into Helium. The solar cloud is almost completely concentrated into several proto-planets.
 
 

9. Solar radiation becomes steady and proto-planets acquire spherical forms.
 
 

10. Our solar system now consists of the Sun, nine large planets, as well as a set of small planets (asteroids), comets, still smaller-sized bodies and cosmic dust.

Our solar system is a part of the system of the Milky Way Galaxy,- and the latter is a component of the Universe - infinite in the time and space of our material world.

Our home, the Earth, is one of the smaller planets revolving around the Sun. The Sun is one of countless billions of stars existing in the Universe. Millions of galaxies are so far from us, that the light from some of these far solar systems began its way to us more than 4.5 billion years ago. Our near-Sun planetary system is probably not unique in the Universe, but the direct proof of existence of other such systems is just emerging.  Only infinitesimally small, periodic movements, noticed by an astrophysicists observing stars nearest to us, give weak, indirect indications that there may be other solar systems similar to ours.

How and when were our solar system and Planet Earth formed? The first written thoughts of Man about the origins of the Universe, solar system and Planet Earth appeared during the 3rd and 2nd millennia BC. Later, observations and opinions of philosophers and scholars of Ancient Greece and Ancient Rome were written and have been translated. For many centuries, however, the teachings of divine creation of the World dominated thought, but alongside them were hypotheses, with striking similarities with modern ideas. The scientist, Heraclitus, of ancient Greece wrote 500 years BC: "The World, uniform as a whole, was not created by Gods or people, and was, is, and will eternally burn, but yet, inflammable and normally fading". The Roman philosopher, Tit Lucretius Car, in the poem "On the Nature of Things," proclaimed the idea that the Universe is infinite and in it there is a set of worlds, similar to ours. Though many theories have been introduced over many centuries, only since the middle of the 20th century has this complicated problem been investigated, on the basis of new scientific data.

By studying the structure of meteorites, scientists have determined their age - about 4.6 billion years old. In making a determination of an absolute age of most ancient rocks of the Earth, an analysis of the distribution of isotopes of the same chemical element over time permits us to make a reasonably accurate age-determination of our planet: 4.5 - 4.7 billion years, as is the age of the Moon and the other planets. These and many other data have gradually resulted in the acceptance of modern cosmogonic hypotheses, a huge role in the development of which was played by the Soviet scientists O. Yu. Shmidt, V.G. Fesenkov, A.P. Vinogradov and others.

Of the modern cosmogonic theories, the most significant is that of the "Big Bang" . According to this theory, the Universe existed in a kind of small volume of super-concentrated substance - "a primitive atom", some 20 billion years ago. As a result of its explosion, a gas-dust cloud was formed, and further condensation within the cloud resulted in formation of the Sun and proto-planets, about 15 billion years after the "Big Bang" - about 5 billion years ago. Another theory, that of pulsation of the Universe has also been presented, noting that the Universe has periodically reached a physical maximum size, after which it compressed into itself to the size of "primitive atom", which in turn, exploded, forming a new Universe.
 

Information provided by HDNO:  http://www.oceansatlas.com/unatlas/about/ContactInfoForHDNO.html