Final answer:
The solar nebula is the original rotating cloud of gas and dust that formed the solar system, which under its gravity collapsed to form the Sun at its center, with the remaining materials eventually forming the planets and other celestial bodies.
Step-by-step explanation:
Definition of Solar Nebula
The term solar nebula refers to the vast, rotating cloud of gas and dust from which the solar system was formed about 4.5 billion years ago. This flattened cloud of cosmic raw material is the precursor to the sun and the planets in our solar system. As gravity caused the solar nebula to collapse, it became hotter and denser at its center, forming the Sun. The remaining material then coalesced into the planets, moons, and other bodies that orbit the Sun. Similarly, the Orion Nebula is a current example of a stellar nursery, where new stars and planets are being formed, likened to a contemporary analog of our own early solar nebula. Unlike the solar nebula which has completed its lifecycle, many young stellar nebulas or circumstellar disks can be observed today, reflecting various stages in the planetary formation process.