The basic question would be that what are Black holes?

Ans) black Holes are a geometrically formed region which has a lot of gravitational pull, such that no particle can escape through it ( even light).

So the question arises that how are black holes formed? 

A black hole forms when any object reaches a certain critical density, and its gravity causes it to collapse to an almost infinitely small point.

What are Stellar-mass black holes? 

Stellar-mass black holes form when a massive star can no longer produce energy in its core. To maintain the position of the star, Gravity causes the core to collapse. the Stars's outer layer may blast away due to the incredible energy, or it may fall into the black hole to make it heavier.

Are there any balck holes close to the earth? 

As such there are no black holes which are close to the earth, hence there is no harm caused to earth and its environment. However, a supermassive black hole is there in the centre of our milky way galaxy, almost 27000 light-years away. hence it completely assures us that it won't affect our solar system. Its mass is several million times the mass of the Sun!

What happens when you get close to a black-hole? 

The effect of a black hole depends upon its mass and size. However, if we talk about a normal size black hole then....  A black hole exerts a very strong gravitational pull on an object. the same pull is responsible for bringing about tides on Earth. Hence when an object reaches near a black-hole, the pull on the one side of the object is much more than the pull on the opposite sides. hence, due to the action of gravity, the object gets pulled apart into many pieces.

 What is the relation between Time and black-hole ?

Many explorers say that Black hole acts as a "Natural Time Machine". By this they mean to say that Balck hole has a deep effect on time, slowing it down more than anything in the galaxy. Example: Let us suppose that there is a bus which is moving around the earth at speed just near to the speed of light. In that bus if a person stands and starts walking, its speed would be very near to the speed of light! but according to a theory in Physics, reaching to the speed of light is not possible, Hence when that person starts walking, the time just gets slower to prevent that person to break the limit of speed. So the person is unable to reach the speed of light. Practically if the Bus starts moving around the earth on Jan 1 2015 and it moves around the Earth for almost 50 years then the time on Earth after 50 years would be Jan 1 2065 but the passengers would feel the journey to be just of 2 to 3 days. This is because time got slower and in just 2 to 3 days they travelled 50 years into the future.

Which is the largest Black-hole in the universe?

The largest black-hole yet discovered is in the galaxy s5 0014+813 in which almost 40000000000 sun's can fit in.

What happens when Two Black-Holes collide?

The results of two black holes colliding has been a debatable topic for all. Results say that when 2 black-Holes collide they will give out ripple(waves) called gravitational waves. When they come together, the black-holes won't be able to escape each others gravitational pull. hence they will combine to form a bigger and stronger black hole. 

What is the WOW! signal?

WOW! signal was founded by a scientist named Jerry Ehman while he was working on a project. The signals were recorded by a microscope. The signals had binary sequence. When the scientist listed it out, he found that the sequence meant the word WOW!. This shows that there are some other species of life which exist in the universe apart from our Milky Way Galaxy.

Q) Now, What do you think would be the brighest thing in the universe?

Ans)  The answer thought by everyone of you would be our sun or any other star. But our sun is not even near to be the brighest thing in the universe. The brighest thing is a quasar. A quasar has an energy equivalent to the combining energy of all the stars in our galaxy (10000000000). Its even more than that. Surprisingly, a quasar which is discovered is 7 billion light years away from our Earth but emits more light than a star which is just 400 light years away.