The preposition is followed by its object (and words that modify the object in the prepositional phrase). A preposition is a word that occurs before a noun/pronoun in a clause. Preposition means, pre-before and position-the object's location.
The most widely accepted scientific explanation for the formation of the Solar System is called the Solar Nebular Model. According to this model, the entire Solar System formed around 4.5 billion years ago from the gravitational collapse of a small fraction of a giant molecular cloud, also known as a nebula.
NASA scientist Jennifer Heldmann describes the most popular theory of how the solar system and Earthâs moon was formed. Below you can watch a short four minute video of her explanation of the accretion theory, see a computer simulation of the hypothesis, or watch the whole 45 minute video as recorded during the âAsk a Scientistâ event in San Francisco, CA, on Oct 7th, 2008.