I am a past student of Tezpur University, and during my M.Sc., I asked this question to Dr. Gulab Chand Dewangan (IUCAA) during a conference organized by the Physics Department (TU). I think his reply was very appropriate.

Studying Astronomy and Astrophysics helps us to understand Physics better. The energy scales and extreme environments in the universe can't properly be simulated in our earth based labs. So, by studying about the celestial objects we can gain a better understanding of the Physics at these extreme scales.

The life on the planet evolved to a state where one of the species evolved a thinking brain capable of inventing tools, music and art. The thinking brain will always ponder about its existence and relevance. All the natural sciences make attempts to address the first issue. The second issue is addressed by philosophy, religion and creativity in the form of art, culture and music.

Inherently, I think that some humans (not all) are explorers...some are hunter gatherers...and these humans are typically inquisitive and want to know the how and why behind what they observe. So, we end up exploring, hunting for and gathering information, and what better quest than delving into the depths of the solar system or the universe....that is where the unknowns, the 'truth', the missing God, the ultimate frontier lies.

The shortest answer I know is

It is the next best thing to being there.

Its for our survival.like charles darwin said only the stronger can survivor.we should atleast know about our surroundings to save ourselves from the dooming black holes and all

“Homo sapience and the Universe” is the central problem of science. Why the Universe is appropriate for homo sapiens? Studying the Cosmos we partially understand the answer to the question. For details see discussion of anthrope principle.

Humans are naturally curious and the cosmos is the biggest mystery. Certainly, survival of the Human race is another reason - because unless humans become spacefaring, any extinction level event that may happen on Earth would wipe us out like the dinosaurs.

I agree to Marshall, we humans are dead curious! I see it every day when my daughter misuses and breaks her toys to see what else one can do with them. The only difference regarding scientists is that they act constructively (or at least they try :-) )

For me, it is the same curiosity that human kind have since its early existence: explore the environment where we are. Nowadays, we have resources to explore even far away from our home. But, in universal terms, the universe is also our home.

The reason is evolutionary. We are curious because all the non-curious among us had odds against them. Natural selection has been filtering curiousity.

But another interesting aspect is that there is a balance. We are curious, but not too curious. There are dangers of being too curious as well. A good example is madam Curie suffering from exposure to radiation.

So, little curiousity and too much of it, both have been providing evolutionary disadvantages.

It is the next best thing to being there.  I was curious at 5 yrs old when i read my first astronomy book.  I was hooked.  After all, we are made of that same Universe and would not exist without it.