The Truth About the Solar System's 3rd Habitable Planet

The Solar System actually has three planets in the "habitable" zone, but British scientists have just delivered some bad news.

In recent years, while Mars has emerged as the leading candidate for the hunt for alien life, Venus has also been noted for its signs of geological activity as well as some special components in its atmosphere.

Both these planets and our world lie within the Solar System's Goldilocks "habitable zone ," thought to have been born with similar characteristics favorable to life.

However, planetary researcher Tereza Constantinou and colleagues from Cambridge University (UK) do not think so.

Venus is sometimes referred to as Earth's "twin planet" - (Photo: NASA).

According to Sci-News, there are two main theories about the evolution of conditions on Venus since its formation 4.6 billion years ago.

• First , conditions on the planet's surface were once temperate enough to sustain liquid water, but the runaway greenhouse effect caused by widespread volcanic activity has made the planet increasingly hotter.
• The second hypothesis suggests that Venus was born hot and liquid water could never have condensed on its surface.

'Both of those theories are based on climate models, but we wanted to take a different approach based on observations of Venus' current atmospheric chemistry,' said Dr Constantinou .

To keep Venus' atmosphere stable, any chemicals removed from the atmosphere must also be returned to the atmosphere, since the interior and exterior of the planet are constantly chemically "communicating" with each other.

In a study recently published in the journal Nature Astronomy, the authors calculated the current destruction rates of water molecules, carbon dioxide and carbonyl sulfide in the Venusian atmosphere.

These must be replenished by volcanic gases to keep the atmosphere stable.

However, new calculations show that, given what exists in the atmosphere today, the planet's volcanic gases contain a maximum of only 6% water.

These dry eruptions suggest that Venus's interior, the source of the magma that releases volcanic gases, is also dehydrated.

With a planet so dry on the inside, it is highly unlikely that liquid water oceans ever existed on its surface.

The results could help astronomers narrow the search for planets that could support life in orbit around other stars in the galaxy.

If Venus is truly uninhabitable, then perhaps we should eliminate planets with similar atmospheric compositions in other star systems from the list of potential habitable worlds, even if they lie within the system's habitable zone.