It has long been speculated that life exists on Mars or atleast existed aeons ago, because of its similarity to Earth in many respects.

· It is also at a fair distance from the sun like the earth, which makes it neither too cold nor too hot.

· The length of a day on Mars is almost the same as that on Earth.

· Its axial tilt is quite similar to ours, which makes it experience seasons just like the Earth.

Earlier, Mars was believed to contain seas, land and complex lifeforms. Some people even went to the extent of claiming to have observed Martian Canals. People’s belief in the possibility of life on Mars became stronger with the release of books like H.G.Wells’ ‘War of the Worlds’ and movies like ‘Mars Attack’, both of which showed the Martians as hostile creatures, trying to invade our planet. Much to the dismay of the alien enthusiasts, space probes like Mariner 4, and the two Mars Exploration Rovers – Spirit and Opportunity, have proved beyond the shadow of a doubt that no life exists on Mars and that it is an arid, uninhabitable place.

The only encouraging evidence for life on Mars came with the discovery of a Martian meteorite – ALH84001 which showed signs of primitive bacterial life that would have existed millions of years ago. The meteorite was found to contain hydrocarbons and mineral phases which are related to microbial activity. Also, tiny carbonate globules were found on the meteorite, which could be the microfossils of primitive bacteria.

Whatever it is, one thing is for certain…at present, life doesn’t exist on Mars and even if it had aeons ago, it was not even close to getting evolved into a complex life form… .

SETI is an acronym for the Search for Extra – Terrestrial Intelligence. (SETI@home is a project undertaken by the Space Sciences Laboratory, at the University of California, Berkeley). SETI was the first large scale project in this direction, a serious attempt to make contact with extra – terrestrial lifeforms, using telescopes, radio and optical signals as a means to establish contact. Radio waves were chosen as the primary form of signal because they can travel extremely long distances, between stars, and we have the technology to send and receive these signals over long distances.

When this project was launched, it had a lot of expectations. Everyone believed that contact would be made atleast in a few years time. Though we have been sending radio signals for almost 50 years, we haven’t actually achieved our goal. All radio, television and radar signals from our planet leak into space and has been spreading across the galaxy. Moreover, a number of experiments have been carried using radio and optical waves, like sending the ‘WOW’ signal etc…. But till now, none of these experiments has proved to be fruitful.

Probably, we are the only intelligent lifeform in the universe, which places us in a very significant position. What a great feeling will that be… . Or perhaps, other intelligent lifeforms have been sending us radio signals and we still haven’t found the right frequencies to receive them i.e. we just haven’t been looking for the right signals, in the right place, at the right time….

Life similar to that on Earth requires carbon, oxygen, nitrogen, phosphorus and sulphur. If any of these were not present, life, as we know wouldn’t have originated and evolved. Apart from this, the planet should be at a particular distance from its star such that conditions (like temperature) are conducive to sustain life, it should have sufficient amounts of oxygen, water etc…. These are the main conditions for life to flourish in a planet. Since the universe is extremely big, it is entirely possible that an infinite number of planets satisfy all these requirements, giving rise to infinite number of civilizations.

Another possibility is that, life on other planets might be entirely different from ours, that we are not able to recognize. For example, silicon might be a substitute for carbon, giving the lifeforms a crystalline morphology and enabling them to exist even at high temperatures or there could be lifeforms that can breathe in Nitrogen and use ammonia as a substitute for water. We never know…

So, we accept that there is a very high possibility that life exists elsewhere. Now, the next question arises. Why haven’t we found one or why haven’t they made contact? Like I said, we probably aren’t intelligent enough to detect an entirely different lifeform. Moreover, how have we tried to make contact? The SETI uses radio frequency signals. Any of these cases is possible:

· Probably, they detected these signals, but are too primitive to know how to respond.

· Probably, their means of communication is entirely different from ours and hence, they did not think these radio signals were sent to make contact.

· In a more likely case - they responded, but we are not intelligent enough to detect or comprehend these signals.

· Probably they are much more intelligent than us that they just don’t care to respond to primitive, unintelligent civilizations.

One of the most interesting aspects of space science is the possibility that life could exist elsewhere in the universe. The thought that we might not be alone in the universe excites us. It might actually be true. The universe is so big that there is a very good chance that there could be infinite civilizations just like us or much more intelligent than us.

I believe you would have watched or atleast heard about the Hollywood movie ET – The Extra Terrestrial, directed by Steven Spielberg. I can still remember every scene from that movie for two reasons: That was the first movie I watched on my computer when I was in sixth grade (and I would have watched it atleast a dozen times), AND before watching this movie, it never struck me that intelligent life could actually exist outside the Earth. In the movie, a young boy named Elliot finds an alien accidently left behind on Earth and befriends it. The rest of the movie is about the bond that develops between the boy and the alien being and how he helps his extra terrestrial companion contact his home planet. I was deeply touched by the movie. Though it seems stupid to me now, as a kid, I actually spent hours on my terrace watching the sky, craving for a intelligent extra – terrestrial life form to land right besides me. I am sure any kid who watched the movie would have tried the same.

There have been a number of occasions when people have speculated to have seen alien beings or alien spaceships (Unfortunately, no direct evidence of any such life form has been found yet). So, we all strongly believe that they are out there somewhere, waiting to be contacted.

So are we alone..?? If not why haven’t we had contact…?? Only time can give us the answer…..

Any idea what will happen to the Sun in the future?? The Sun has been shining for about 4.5 billion years due to thermonuclear fusion of hydrogen to helium. But, we all know that the hydrogen supply cannot last forever. The sun will eventually run out of fuel. That triggers the dramatic chain of events and the sun will undergo a radical change.

Once the hydrogen supply gets exhausted, the nuclear fusion in its core would stop. The core starts contracting under its own gravity and more importantly the outer shell swells considerably, which decreases its surface temperature and the sun becomes a giant red ball of gas – A Red Giant Star. The sun will swell up to such an extent that it will swallow all the inner planets including the Earth (It is estimated that in its red giant phase, the Sun will expand out to a radius of approximately 1 AU [AU – Astronomical Unit = 150,000,000 km], which is 250 times its present size). So that’s going to be the end of the Earth…Doomsday…

Good News!!! Fortunately for us, none of this is going to happen in the near future. It is estimated that the hydrogen fuel in its core will last atleast for the next 5 billion years. By the time all these happen, Mankind or any form of life, for that matter, might not even exist on Earth.

Slowly, our star continues to collapse under its own gravity and shrinks further. The gravitational field will eventually become so great that nothing can escape its pull, even light. Around the black hole, a boundary in space-time is formed which is called the Event Horizon. We should be nowhere close to the event horizon because any object which falls inside this has no chance to escape from it. So it’s wise to move as far away from it as we can and observe the black hole from a peaceful area.

We cannot actually see a black hole with our naked eye or using a telescope. Because it absorbs all the light that falls on it, reflects nothing just like a perfect black body. But watch the stars around it closely. The stars close to this black hole start rotating this seemingly empty region in space. The main feature of a black hole is its interaction with other objects in its vicinity. Gas from the nearby stars, like in the case of a binary star system, feed the blackholes and make them grow stronger. Sometimes, these blackholes merge with other stars or objects, which are suspected to be main reason for the formation of Supermassive blackholes in the center of most galaxies. All the matter, that enters the event horizon is accelerated towards the exact center, called the Singularity, where the gravitational pull is so strong and matter is crushed to infinite density.

Guess we have spent enough time in the past studying the life of this star which is going to remain a blackhole for eternity. So let’s come back to the present and see if we can spot this blackhole….wink! Wink!

Stars having masses similar to that of the sun become a White Dwarf after losing their expanding outer shell. The outer shell expands so much that it escapes the star’s gravitational force. White Dwarfs are very small, dense, hot stars whose nuclear energy supplies have been used up. They spend several billion years in this phase and eventually cool and fade out. So nothing dramatic happens during the final stages of these stars….So boring!!!

Don’t worry….our star is a massive one…so lets see what happens to it. The fusion in its core continues till so much iron gets accumulated in the core, that it is not able to support its own mass. Now, the most spectacular thing happens. The core suddenly collapses causing the electrons to collide with the protons to form neutrons or neutrinos. This sudden collapse produces shockwaves and causes the entire star to explode. This is called the Supernova Explosion. Supernovae are so bright that they can be easily spotted with the naked eye even if they are not normally visible. They can last for several weeks or months and during this short period they radiate as much energy as the sun does during its entire lifetime. Supernova is an important source of heavier elements in the universe and plays a very significant role in the formation of new stars.

After the supernova explosion, the remnants either become a Neutron Star or a Black Hole. Neutron Stars are extremely dense stars (a mass 3 to 4 times that of the sun is accommodated within a diameter of a few kilometers). However, the remnant left by our star after the explosion is greater than 4 times that of the Sun…which means that our star is going to turn into one of the strangest and most mysterious objects in the universe….A BLACK HOLE!!!