After decades of searching for signs of life in the stars, the very thing we've been looking for may have been on our galactic doorstep all along. A recent article in the Astrobiology journal suggests there may be life in the clouds of Venus. An international team of scientists, including researchers from the University of Wisconsin-Madison, have used evidence from new Venus footage to make these speculations. While Venus’ atmosphere has everything micro-organisms would need to survive, the study authors won't know what's really going on until they send a floating aircraft to comb the skies of Venus.

While the surface of Venus is much too hot and unfriendly to support life as we know it, the same cannot be said for the skies. Dark patches in the clouds of the Venusian atmosphere could be caused by light-absorbing bacteria, with micro-organisms in the clouds protected from the conditions below. According to researchers, once you get to an altitude of 46 kilometres, the pressure drops to a level that is similar to sea level on Earth. While the temperature up there is still a toasty 60 degrees Celsius, life in the form of bacteria would have everything it needs to survive.

According to University of Wisconsin-Madison scientist Sanjay Limaye, who led the new study, “Venus has had plenty of time to evolve life on its own." Some models suggest that Venus once had a habitable climate with liquid water on its surface for as long as 2 billion years, a period of time “That’s much longer than is believed to have occurred on Mars." While clouds of sulphuric acid, ultra-high atmospheric pressure, and 465 degree temperatures rule out the possibility of life on the surface of Venus, the same cannot be said for the clouds.  

Even though the days of surface life on Venus are well and truly over thanks to its runaway greenhouse climate, "Venus shows some episodic dark, sulphuric rich patches, with contrasts up to 30–40 percent in the ultraviolet, and muted in longer wavelengths. These patches persist for days, changing their shape and contrasts continuously and appear to be scale dependent." said Limaye. The dark patches look similar to algae blooms found in Earth’s own lakes. Because they also have similar dimensions to these algae blooms, the probability of them having life is high.

This is not the first time that cloud-based life on Venus has been speculated, with American and Soviet probes first noting the ideal pressure and temperature conditions in the 1960s. Carl Sagan even co-authored a paper with noted biophysicist Harold Morowitz about the subject, saying "While the surface conditions of Venus make the hypothesis of life there implausible, the clouds of Venus are a different story altogether." It wasn't until Limaye recently learned about the light-absorbing properties of bacteria on Earth that he decided to take another look. In order to study the unknown UV absorber properly, however, a hypothetical aircraft that floats above the skies of Venus is needed to take samples of the Venusian atmosphere. 

Image source: NASA Images/Shutterstock