Is there life on Venus? Scientists detect traces of phosphine and ammonia in the planet’s clouds – and say they could be coming from microbes
With its boiling temperatures and acidic clouds, it’s one of the most formidable worlds in our solar system.
But exciting new findings suggest life may exist on Venus, the second planet from the sun.
Researchers have confirmed traces of ammonia and phosphine in the planet’s clouds – two potential ‘biomarkers’ that are indicative of life.
On Earth, both compounds are produced during the decay of organic matter, such as plants and animals.
Because there are currently no other known natural processes for its production on Venus, it could be being produced by something scientists aren’t aware of.
It follows the original detection of phosphine in Venus’ clouds in 2020 – although the findings were disputed.
The new findings were presented at the National Astronomy Meeting 2024 at the University of Hull on Wednesday.
Professor Jane Greaves, an astronomer at Cardiff University and author on the findings, said ammonia has been seen before in the solar system, but in the gas giant planets Jupiter and Saturn.
‘It’s natural there because their gas is mostly hydrogen,’ she told MailOnline.
‘It’s much rarer on the rocky planets like Earth or Venus.’
Ammonia is a colorless, poisonous gas that occurs in nature, primarily produced by anaerobic decay of plant and animal matter.
Professor Greaves and colleagues detected the gas in Venusian clouds using the Green Bank telescope in West Virginia.
The giant 2.3-acre dish detects weak radio waves that rain down on us from objects in space.
‘In simple terms, the Green Bank telescope takes a rainbow of light except it does it in radio light,’ Professor Greaves said.
‘Where there is some missing light, that’s because a molecule has mopped it up and we use the exact wavelength to identify the molecule.’
The ammonia was detected in the upper parts of the planet’s clouds where it’s too cold for life to exist.
However, there is the possibility that the ammonia could also be in the deeper, warmer area of the clouds and is then rising to the upper parts.
That will be what the researchers will try to establish next.
Meanwhile, phosphine was discovered by a team led by Professor Greaves and Dr Dave Clements at Imperial College London’s physics department, by studying data from the James Clerk Maxwell telescope in Hawaii.
Phosphine, a colourless gas that smells like garlic or decaying fish, is naturally produced on Earth by certain microorganisms in the absence of oxygen.
It can also be released in small amounts from the breakdown of organic matter, or industrially synthesised in chemical plants.
Dr Clements stressed that the detection of both these gases on Venus is not evidence that life exists there and it’s unknown what processes are emitting them.
‘It is most likely some chemical process that we don’t currently understand and don’t know about,’ he told MailOnline.
‘But phosphine has been proposed as a biomarker for exoplanets [planets outside our solar system], and on Earth it is only found in association with life, so life is also a possibility.
‘At this stage we just don’t know – more observations and more lab and theoretical work is needed to understand what’s going on, and maybe future missions to Venus will help as well.’
Venus is known as Earth’s ‘evil twin’ because its also rocky and about the same size, but its average surface temperature is a blistering 870°F (465°C).
Thanks to its dense atmosphere, Venus is even hotter than planet Mercury, even though the latter orbits closer to the sun.
The rocky sphere is not only inhospitable but also sterile – with a surface hot enough to melt lead and toxic clouds of sulfuric acid.
Because the clouds are so acidic, the phosphine would be broken down very quickly and must therefore be being continually replenished.
However, it’s generally believed in the astronomical community that the planet was not always such an unwelcoming place.
Perhaps as recently as 700 million years ago, Venus likely had oceans similar to Earth’s – and could have harbored life as we know it today.
But these oceans boiled away when our neighbouring planet underwent ‘a runaway greenhouse effect’ – a dramatic escalation in temperatures.
It was back in 2020 that scientists revealed traces of phosphine gas in the planet’s clouds which they said could be coming from microbes.
At the time, Professor Greaves and colleagues observed Venus using both the James Clerk Maxwell Telescope at Hawaii’s Mauna Kea Observatory and the Atacama Large Millimeter/submillimeter Array in Chile.
They detected a so-called ‘spectral signature’ that is unique to phosphine and estimated that the gas is present in Venus’ clouds in an abundance of around 20 parts-per-billion.
However, other scientists claimed not to be able to find the same signal and members of Greaves’ team admitted to a calibration error and downgraded the strength of their claims.
Now, using the James Clerk Maxwell telescope once more, Dr Clements has been able to find phosphine again, and he thinks it may get destroyed by sunlight during the day.