GENERAL KNOWLEDGE

Detailed explanation-1: -Nebulae are made of dust and gases-mostly hydrogen and helium.

Detailed explanation-2: -Dark Nebula-A dark nebula is a cloud of dust that blocks the light from objects behind it. They are very similar to reflection nebulae in composition and look different primarily because of the placement of the light source. Dark nebulae are usually seen together with emission and reflection nebulae.

Detailed explanation-3: -CO and H2 are the most common molecules in interstellar gas clouds. The deep cold also causes the gas to clump to high densities. When the density reaches a certain point, stars form. Since the regions are dense, they are opaque to visible light and are known as dark nebula.

Detailed explanation-4: -Most stars are born inside great clouds of gas and dust called nebulas. The process begins when a nebula starts to shrink, then divides into smaller, swirling clumps. Each clump becomes ball-shaped, and as it continues to shrink the material in it gets hotter and hotter.