Solar nebula
In cosmogony
Cosmogony, or cosmogeny, is any scientific theory concerning the coming into existence or origin of the universe, or about how reality came to be. The word comes from the Greek κοσμογονία , from κόσμος "cosmos, the world", and the root of γίνομαι / γέγονα "to be born, come about"...

, the nebular hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System
Formation and evolution of the Solar System
The formation and evolution of the Solar System is estimated to have begun 4.568 billion years ago with the gravitational collapse of a small part of a giant molecular cloud...

. There is evidence that it was first proposed in 1734 by Emanuel Swedenborg
Emanuel Swedenborg
was a Swedish scientist, philosopher, and theologian. He has been termed a Christian mystic by some sources, including the Encyclopædia Britannica online version, and the Encyclopedia of Religion , which starts its article with the description that he was a "Swedish scientist and mystic." Others...

. Originally applied only to our own Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

, this method of planetary system formation is now thought to be at work throughout the universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

. The widely accepted modern variant of the nebular hypothesis is Solar Nebular Disk Model (SNDM) or simply Solar Nebular Model.

According to SNDM stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC).