I think we're alone now: Does life exist on other planets?
In this guest article, Sarah Cruddas, co-star of Craig Charles: UFO Conspiracies, and author of new book, Look Up: Our story with the stars tackles one of the biggest mysteries in the universe.
Are we alone?
The one thing you likely have in common with your ancestors is that you, like them, have looked up at the night sky. On a clear night, away from other light sources, a universe full of possibilities lies before us. Twinkling stars, the hazy stretch of our galaxy the Milky Way, the tiny glowing orbs of some of the planets in our solar system and the bulging belly of the Moon – a sight which throughout our history has cast a glow over lovers and poets, scientists and dreamers.
In many ways, the experience of seeing the night sky is like looking out of a window of our spaceship – Planet Earth – into the vastness of the cosmos that we are a part of. It is an impossibly large cosmos, to put a number on it, our visible universe is estimated to be 93billion light-years across - so large that its size is perhaps beyond the comprehension of the human mind. It is also a place of wonders beyond the imagination. To paraphrase the evolutionary biologist JBS Haldane 'The universe is not only as strange as you can imagine, it is stranger than you can imagine.'
Yet in this frighteningly large universe – of which we know so little about - we only have one sample of life. Us. And all of the estimated 8.7million species we share our Earthly home with. Despite all our advances in science and technology, the question of ‘Are we alone?’ still remains one without a substantial answer.
Of course, that is not to say we haven’t thought we haven’t come close. During the late 19th century the mistaken observation of ‘canals’ on the planet Mars had led some of the brightest minds to conclude that a technological civilisation existed on the Red Planet. It wasn’t until the birth of the Space Age when robotic spacecraft visited Mars that it was shown that there were no such engineered canals or signs of an intelligent civilisation.
Later, in the 1990s, the possibility of life on Mars was once again in the headlines, with claims of microbial life discovered in a Martian Meteorite – which prompted a speech from then-President Bill Clinton about the almost unfathomable implications of the discovery. Yet there was much doubt cast over the discovery – and to date – while Mars remains a likely place for past or present microbial life (with the most recent robotic mission to the planet – NASA’s Perseverance – working under the mission objective of hunting for evidence of ancient microbial life) there is yet to be strong enough scientific evidence to conclude that life of any form has or does still exist on the planet.
There have also been observations closer to home which has led some to speculate about the possibility of life elsewhere in the Universe. While unexplained sightings in the sky are nothing new, incidents such as the now infamous 2004 Nimitz Tic Tac – and more recent sightings made by pilots have added more credibility to how serious some say we should be taking unexplained aerial phenomena.
Perhaps the most intriguing is a mysterious object called ʻOumuamua. The first interstellar object ever detected moving through the solar system, its unusual cigar shape left many questions in the scientific community, with some being as bold to postulate that this could have potentially been an extra-terrestrial craft passing through our solar system. The answer to whether it was or not, we may never know.
Most likely though the answer to one of the most profound questions of all time ‘Are we alone?’ lies closer to our cosmic neighbourhood. And it is no longer a case of ‘if’, but more likely ‘when’ we will be able to say we are not.
Today we know that life on planet Earth can survive in much more extreme environments than we ever thought possible. Even at the depths of the ocean in darkness and under extreme pressure alien-like life has been found to exist. Couple this knowledge with the number of candidates for life within our own solar system and the advances in space exploration technology and the possibility of answering the question edges closer.
From icy moons with probable liquid oceans – such as Europa and Enceladus (which orbit Jupiter and Saturn respectively) to Titan – another moon of Saturn, which has its own atmosphere and resembles conditions on an early Earth, to Mars, and perhaps even Venus, where the possibility of microbial life has been postulated to exist in the clouds.
As space missions advance and more scientific evidence is gathered, we may well be able to – in the next few decades – answer that all-important question of whether we are alone. Even though life discovered elsewhere in the solar system is likely to be microbial – simple, single-celled life – if it is proved to be life that has originated independently of life on Earth, that would mean two geneses in our one very average solar system. And we of course know that the universe is teeming with solar systems, the likes of which we cannot yet fully imagine.
Then, the question then becomes ‘Are we the most intelligent species?’.
I hope the answer is no.
