The accretion model, also known as planetesimal assembly, is what gives us the perspective for the formation of the astronomical objects via the process of accretion. Some of the astronomical objects that are formed by this process are the galaxies, stars, planets,and moons. The process of accretion represents the accumulation of particles into an object by gravitationally attracting more and more matter, mostly gaseous matter, forming an accretion disk.
Today the world's population is 7.5 billion. The world's population is changing because of the natural increase rate. The natural increase rate is the crude birth rate minus the crude death rate. Since the crude birth rate is higher than the crude death rate today, this would lead to a higher natural increase rate.
