Without nebulae stars would not exist in our skies. A nebula is a huge cloud of gas and material that appears to be solid. However, it is mostly composed of dust and gas, slowly condensing into stars. Stars come into existence in the vast clouds of dust and gas that move through space. A star begins to form when a large number of gas particles whirl together within such a cloud. The whirling particles attract more particles, and as the group of particles slowly gets larger and larger, its gravitational pull gets stronger. The particles form a giant ball of gas. As the ball grows larger, the particles press down on those below them and pressure builds up inside the ball. Finally the pressure becomes strong enough to raise the temperature of the gases, and the gases begin to glow. When the pressure and temperature inside the ball get very high, nuclear reations begin to take place and form a star.
FACT FILE
A black hole is not really a hole but a very tightly -packed object. It is solid and does not reflect any light, so it looks like a hole!
resources: Tell me why (Chancellor Press)
image 1: https://i2.wp.com/www.astronomytrek.com/wp-content/uploads/2014/12/nebula.jpg?fit=678%2C381
image 2: http://www.penny4nasa.org/wp-content/uploads/2014/01/Black_Hole_Milkyway.jpg