(Image: Wayne Englund)
There was a time when it was generally accepted wisdom that humanity represented the pinnacle of creation - nothing like us, or anything living thing for that matter, to found anywhere apart from this one little rock we call Earth.
That view of life as something of a fluke or divine one-off has been changing for a while now.
There is still a lot we don't know about all the steps to life from no-life but these days both popular and scientific opinion largely concedes that maybe, what we have going on here on this planet isn't quite as unique as we once believed.
And, with that change in perspective, that life and possibly even intelligent life could exist somewhere else in the universe, we started to look for it.
Early on this search focused on our own solar system with NASA's Viking landers looking for signs of life in the Martian soil way back in the 1970s.
The experiments found no evidence of biological activity.
More recently, the discovery of exoplanets orbiting distant stars has given astrobiologists new hope that at least one could provide the conditions necessary for life to get going.
We now know at least 3,458 other worlds exist out there with at least some, such as the four in the newly discovered TRAPPIST-1 system, bound to lie inside their star's 'habitable zone'.
As exciting as an exoplanet discovery is, the vast distance between Earth and any other star system means that directly testing it for signs of life in the way we have done on Mars is almost impossible except over the longest of timeframes.
The scale of the universe is a major challenge in the search for extra-terrestrial life, which is partly why the search for extra-terrestrial intelligence is hoping that any life out there will one day reach out to us.
The SETI cause received a major boost last year when Yuri Milner and Stephen Hawking announced $100 million for their Breakthrough Listen project.
It's a big development with Australia playing a key role - the radio telescope at Parkes has been made responsible for monitoring the southern sky for any signals from ET.
So far, we've heard nothing. But, who knows about tomorrow ?
