Is this newly discovered solar system proof we’re not alone?
FOR centuries it has been one of the most vexing mysteries for mankind: are we, the seven billion inhabitants of this wondrous blue planet really alone, or is there life somewhere out there in the universe?
Yesterday, we came a step closer to answering that tantalising question with the landmark announcement by Nasa scientists of the discovery of a new solar system that has at least three Earth-like planets — with climates that just might support life.
The kind of planets that a certain ET might have called home.
The discovery by an international team using advanced telescopes in space and at far-flung locations around the world has caused a frenzy of excitement among astronomers who, as a breed, are not given to hyperbole.
However, it is being described as the ‘holy grail’ for researchers.
The intriguing new planets are comparatively near neighbours, too, at just 39 light years from Earth. Granted, 39 light years (234 trillion miles) is hardly a short hop.
But that relative proximity will enable astronomers with ultra- sophisticated telescopes and scanners to focus on the planets and confirm if there is water and the benign atmosphere needed for life to thrive.
Thomas Zurbuchen, associate administrator of Nasa’s Science Mission Directorate in Washington DC, said yesterday: ‘These questions about “are we alone” are being answered as we speak, in this decade and the next decades. This story gives us a hint that finding a second Earth is not just a matter of if, but when.’
Scientists have long speculated that life- supporting planets must exist somewhere in the universe, but none has ever yet been confirmed as potentially life-sustaining.
Now astronomers say they have detected no less than seven Earth-sized worlds orbiting a red dwarf star — the equivalent of our sun — called TRAPPIST-1.
The seven planets are believed to be at least a billion years old and, in theory, all could have lakes and oceans. But three are too close to the star and, therefore, likely to be too hot to have water, while the furthermost planet is too cold.
It is the three planets in the middle (named TRAPPIST-1 ‘e’, ‘f’ and ‘g’) that are generating the most interest as they lie in what is known as the habitable ‘Goldilocks Zone’ — neither too hot nor too cold for life to thrive.
The surface temperatures range from zero to 100c, so water won’t boil off as vapour.
In addition, planet ‘e’ is very close in size to Earth and receives about the same level of light from its star.
Planet ‘f’ is potentially waterrich and gets about the same amount of light as Mars. Planet ‘g’ is the largest: its radius is about 13 per cent larger than Earth’s.
Measurements of the planets’ density suggest the innermost six are rocky, too, just like Earth.
No other known star system contains such a large number of Earth- sized and probably rocky planets, another factor in encouraging life to form.
The research, published in the journal Nature, was led by the STAR Institute at the University of Liege in Belgium.
It used Nasa’s orbiting Spitzer Space Telescope in addition to ground-based facilities, including the Liverpool Telescope, operated by the Liverpool John Moores University (LJMU) Astrophysics Research Institute (ARI).
Dr Chris Copperwheat, an astronomer from LJMU, who coled the international team, says: ‘The discovery of multiple rocky planets with surface temperatures that allow for liquid water make this amazing system an exciting future target in the search for life.’
In fact, it was the robotic telescope operated by LJMU that played a major role in the discovery.
Located on La Palma in the Canary Islands, it detects planets using the ‘transit’ method.
It monitors dips in the light output of a star — in this case TRAPPIST-1 — caused by planets passing, or transiting, in front of it and allows astronomers to infer information about size, composition and orbits.
TRAPPIST-1 is in the constellation of Aquarius: perhaps appropriately, the ‘water carrier’.
It is very small for a star — its mass is less than a tenth of our Sun’s and only marginally bigger than Jupiter.
It is described as a ‘quiet’ star, emitting some solar flares, but not
‘Finding a second Earth is a matter of when — not if’
strong enough to wipe out life. It is because the star is so dim that the planets orbiting it are warmed gently, despite having orbits that are much smaller than that of Mercury, the planet closest to the Sun in our solar system.
The three most promising planets receive similar amounts of solar energy to Venus, Earth and Mars, and Nasa’s Hubble Space Telescope is already searching for atmospheres around them. Some scientists are predicting we will know within a decade if any of the planets harbour life.
And if there are life forms, they will have had much longer to evolve than we have on Earth — thanks to their relatively low temperature, dwarf stars such as TRAPPIST-1 burn through their supply of hydrogen less rapidly than stars such as the Sun. While the Sun has an estimated lifetime of ten billion years, dwarf stars may exist for trillions.
As well as focusing on the new solar system, the international team of astronomers will go on to search 1,000 of the nearest ultracool dwarf stars to Earth in the hope of identifying more Earthlike planets in new solar systems.
Indeed, experts at Nasa’s Science Mission directorate say the project is in the ‘gold rush’ phase. Dr Emmanuel Jehin, another member of the Liege team, says: ‘With the upcoming generation of telescopes, such as the European Extremely Large Telescope and Nasa’s James Webb Space Telescope, we will soon be able to search for water, and perhaps even evidence of life on these worlds.’
The announcement yesterday prompts another intriguing and much debated question: if there is intelligent alien life on a planet orbiting TRAPPIST-1, why hasn’t it made the effort to get in touch with us or even come visiting?
This is especially pertinent if the aliens there have had an evolutionary head start on us lasting billions of years.
This is the famous conundrum dubbed the ‘Fermi Paradox’. Back in the Forties, the renowned Italian physicist Enrico Fermi suggested that, with 100 billion stars in our galaxy, it was logically inevitable that intelligent life should have evolved elsewhere in the universe.
What’s more, he added, a highly evolved extra-terrestrial life-form should surely have colonised the galaxy by now.
So, Fermi asked, where are all the aliens?
The paradox has become more ever more baffling as our knowledge of the universe grows.
As well as the newly found planets orbiting TRAPPIST-1, deep space scans performed by Nasa have discovered a further nine potentially life- supporting planets farther away.
Some scientists go so far as to speculate that there may be around 60 billion planets capable of supporting life in the Milky Way alone.
Yet 40 years of intensive searching for extra-terrestrial intelligence has yielded nothing. No radio signals, no credible spacecraft sightings, no close encounters of any kind.
Geoffrey Miller, an evolutionary psychologist at the University of New Mexico, has proposed a disturbing answer. Perhaps there is a limit to how sophisticated a species can become.
We become smart enough to make nuclear bombs — and dumb enough to use them, he says. Or perhaps we just get addicted to social media and computer games, Miller suggests facetiously.
‘The aliens may forget to send radio signals or colonise space because they are too busy with runaway consumerism and virtual reality narcissism . . . just as we are doing today,’ he says.
With the discovery of TRAPPIST-1’s Earth-like planets, we have a chance to find out whether current theories about alien life hold any truth.
But less we expect too much, a word of caution from Astronomer Royal, Lord Rees: ‘Even if conditions are close to Earth-like, the mysteries of biology remain.
‘We know how simple life evolved into our present biosphere. But we don’t know how the first life was generated from a “soup” of chemicals.
‘It might have involved a fluke so rare that it happened only once in the entire galaxy — like shuffling a whole pack of cards into a perfect order.’
On the other hand, this crucial transition might have been almost inevitable given the ‘ right’ environment.’ Watch this space.
If alien life is out there, why don’t they get in touch?