Dr. Michelle Thaller, a NASA scientist, has put forward a compelling theory that hints at the potential existence of aliens on Venus, a planet characterized by scorching temperatures reaching 475°C (900°F) and an enveloping, thick acidic atmosphere.

Dr. Thaller's theory proposes that while Venus remains inhospitable to humans due to its extreme conditions, aliens could potentially be hiding there, adapted to the planet's harsh environment.

A research scientist at the Goddard Space Flight Centre in the US, Dr. Thaller highlights "possible signs of life" that have been detected within Venus's carbon-dioxide-rich atmosphere. She expresses confidence in the existence of life beyond Earth.

In an interview with The Sun, Dr. Thaller said: “We see possible signs of life in the atmosphere of Venus.” 

“I never expected Venus. Venus is now one where we see something in the atmosphere that looks very much like it could be produced by bacteria.” 

Despite Venus being often referred to as Earth's twin due to its similar size and structure, it presents an environment utterly hostile to human survival.

Professor Dominic Papineau, an astrobiologist at the University College of London, offers a more cautious perspective on Dr. Thaller's views, considering them "difficult to realistically hypothesize."

Professor Papineau emphasizes the necessity of liquid water for life-related chemical reactions to occur. While he acknowledges that Venus may have had liquid water in the past, he points out the challenges of sustaining life there today due to its extreme surface conditions and volcanic activity.

Both Professor Papineau and Dr. Thaller agree on the potential for microbial life on the solar system's icy moons. While Venus poses challenges, they concur that Mars and the icy moons of the outer solar system, such as Europa and Enceladus, hold greater promise for the search for extraterrestrial life and the preservation of potential fossils. Liquid water exists on these bodies, and their geological histories suggest they could harbor clues to the existence of past or even present life.