It isn't necessary to guess or speculate. We can directly SEE the ancient universe at the moment it first became transparent to visible light! From such observations we know that the universe is 13.8 billion years old and became transparent to visible light about 380,000 years later. A cosmic "Dark Age" stretched from then until the era in which the earliest stars and galaxies began to form, around 350 million years after the Big Bang. By a billion years after the Big Bang, heating of interstellar gas and dust by the ever-increasing number of stars and galaxies had forever ended these Dark Ages.

Here is one of the earliest galaxies to form in the universe as observed to date, just 700 million years after the Big Bang. It can be seen in the infrared by using foreground galaxies as a gravitational lens. In December of 2012 a galaxy was spotted that formed just 380 million years after the Big Bang..

Young stars forming from huge clouds of gas and dust can be observed everywhere in our galaxy, particularly using infrared telescopes to penetrate the clouds. Star formation is an always ongoing process. As stars form, very often a planetary system forms from the same cloud of gas and dust, and the more massive planets survive when the star "lights up" and blows away the gas and dust from the inner solar system. Recently reported preliminary results from the Kepler Space Telescope indicate that half of all stars have planets, and 0.5% of all stars have rocky planets at such a distance that they could have liquid water on the surface! There might be 1,500,000,000 approximately earthlike planets in our galaxy alone!!

Planetary systems form all the time, and the dark planetary disk nebulae of gas, dust, rock and ice are easy to observe surrounding young stars against a background of distant nebulosity, for example in Orion.