To form a nebula, (gravity / heat / pressure) pulls matter together or causes (pressure change / infrared light emission / an explosion).
To form a nebula, gravity pulls matter together or causes a pressure change.
To form a nebula, gravity pulls matter together.
To form a nebula, gravity pulls matter together or causes a pressure change.
Explanation:
A nebula is a large cloud of gas and dust in space. It is formed through the gravitational collapse of a giant molecular cloud, which consists of gas and dust particles spread across vast regions of space.
Gravity plays a crucial role in the formation of a nebula. As the particles within a giant molecular cloud come closer together, the force of gravity becomes stronger, pulling the matter inward. This gravitational pull starts to bring the gas and dust particles closer and closer, causing them to clump together.
As the clumps of matter continue to accumulate due to gravity, they gradually grow in size, forming a dense region within the cloud. This dense region is known as a protostar or a stellar nursery, where the formation of stars takes place.
Moreover, the compacting of matter in a nebula increases its density, which in turn leads to higher pressure within the cloud. This increased pressure further facilitates the collapse of the cloud, aiding in the formation of stars.
So, in summary, it is the force of gravity that primarily pulls matter together within a giant molecular cloud, consequently leading to the formation of a nebula. Additionally, the increase in pressure caused by the gravitational collapse helps drive the formation of stars within the nebula.