Scientists have new reason to suspect there is extraterrestrial life, after discovering a gas on Venus that is also produced on Earth.

A simple detention of phosphine gas has molecular astrophysicist Clara Sousa-Silva thinking “we are not alone”.

As “fantastical” as it might sound, that is the most plausible explanation, she said.

The study co-author went so far as to suggest “life itself must be very common” and “there must be many other inhabited planets throughout our galaxy” – if it is, in fact, phosphine.

She emphasised, however, that “life, as an explanation for our discovery, should be, as always, the last resort”.

The discovery of phosphine gas in the clouds of Venus could possibly indicate signs of life on the planet. Photo: ESO/M. Kornmesser/L. Cal/ NASA/JPL/Caltech

So, what has phosphine got anything to do with indicating life on what has long been considered an inhospitable planet?

On earth, phosphine is produced by bacteria thriving in oxygen-starved environments.

It is highly toxic to people.

Phosphine was seen at 20 parts-per-billion in the Venusian atmosphere, a trace concentration.

The international scientific team first spotted the phosphine using the James Clerk Maxwell Telescope in Hawaii and confirmed it using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope in Chile.

“I was very surprised – stunned, in fact,” said astronomer Jane Greaves of Cardiff University in Wales, lead author of the research published in the journal Nature Astronomy.

Everything you need to know about the exciting announcement that phosphine has been detected in the atmosphere of Venus. Let's start off with the 60 second overview.. #Venus #VenusNews pic.twitter.com/56dlo7puaZ

— Royal Astronomical Society (@RoyalAstroSoc) September 14, 2020

The existence of extraterrestrial life long has been one of the paramount questions of science.

Scientists have used probes and telescopes to seek “bio-signatures” –indirect signs of life – on other planets and moons in our solar system and beyond.

Earth-based telescopes like those used in this research help scientists study the chemistry and other characteristics of celestial objects.

Ms Greaves said the researchers examined potential non-biological sources such as volcanism, meteorites, lightning and various types of chemical reactions but none appeared viable.

The research continues to either confirm the presence of life or find an alternative explanation.

-with AAP