How the moon and the star came to be?

Answer 1

I'm guessing you mean our Moon and Sun.

Our universe began roughly 15 billion years ago and the first stars and consequent galaxies were formed shortly thereafter. But like just about everything, these primitive stars and galaxies did not last forever. They began to collapse and explode.

That created a lot of space dust and debris. And all that mass began to run into each other and clump together in a process called accretion. Some of those clumps were very very large. So large in fact that their own gravity caused the mass to compact and build up pressure causing consequent heat. Eventually, nuclear fusion, where hydrogen merges to form helium, began in those bigger clumps. That fusion reaction releases a whole lot of energy as light and heat.

And over 4 billion years ago that fusion happened in one big clump and our Sun was born. There were also smaller clumps of space debris that did not fuse. One of those formed our planet...Earth. When Earth first formed it was a mass of molten material and it was frequently bombarded by meteoroids.

Our Moon, on the other hand, did not form through accretion of space dust and debris. Consensus is that our Moon is actually the result of a comet or large meteoroid skimming over our planet while Earth was mostly molten. And that knocked a large volume of the molten planet into orbit around the Earth. That became our Moon. That happened around 3 billion years ago.

Answer 2

In astronomy, the moon was formed from debris left over after a Mars-sized body collided with Earth during its early formation. Stars are formed from collapsing clouds of gas and dust in space, where gravity causes the material to heat up and nuclear fusion reactions take place. This releases energy in the form of light and heat, making stars shine.