Could life possibly exist on Venus? asks Professor Donald Kurtz
Venus is the beautiful, bright “evening star” you can now see to the northwest as twilight fades. It will remain in our evening sky until the end of February next year.
However, Venus is not a star. It is a rocky planet that is a near twin to our Earth in size. But it is 30% closer to the Sun, and therein lies all the difference.
When I was a child growing up in California, I was fascinated by the 1959 slapstick space movie, “Have Rocket, Will Travel”, in which the Three Stooges accidentally (don’t ask) blast off for Venus. There they meet a talking unicorn and a fire-breathing tarantula – great stuff for a child’s imagination.
And in the 1950s it was not so far-fetched to think that Venus might be habitable. Although it receives nearly twice as much energy in sunlight as the Earth, it is more than twice as reflective, so less of the Sun’s energy reaches the ground than on Earth. In my child’s mind, it was plausible that Venus could have a menagerie of alien creatures.
But in the 70 years since then Russian probes have landed on the surface and the NASA Magellan Satellite orbited the planet from 1990 to 1994 using radar to penetrate the thick clouds that block any view of the surface. Venus turns out to be completely covered in volcanic lava less than 500 million years old. OK, that sounds a long time, but here in South Africa, beautifully visible to the eye along the Geotrail above Barberton (a UNESCO World Heritage Site) are surface rocks as old as 3.5 billion years!
Other studies showed Venus’s atmosphere is 96% Carbon Dioxide (CO2), the potent greenhouse gas that is causing climate change here on Earth, where it makes up only 0.04% of the atmosphere. The CO2 traps heat and Venus is the hottest planet in the solar system – even hotter than Mercury, which is much closer to the Sun. The surface of Venus is 460C!
The thick atmosphere has a surface pressure 90 times what it is on Earth at sea level.
I was born and grew up in San Diego, California. In the 1960s a friend of mine from there, Andy Young, who was then working at the Jet Propulsion Laboratory, showed that the clouds of Venus are made of concentrated sulphuric acid!
If you could go to Venus and stand on the surface, as the Three Stooges did in “Have Rocket, Will Travel”, you would be suffocated by the CO2, fried by the temperature, crushed by the pressure and dissolved by the clouds.
This is no place for life!
Or is it?
In 2020 a group of astronomers led by Professor Jane Greaves of Cardiff University reported in the prestigious journal, Nature Astronomy, the discovery of Phosphine (a molecule with one Phosphorous atom and three Hydrogen atoms, hence PH3) high in the atmosphere of Venus where the temperature and pressure are similar to what we enjoy here on Earth.
Phosphine is a nasty-smelling toxic gas produced by decaying plants and bacteria. There is no known way to produce it in the conditions in Venus’s atmosphere, except by life processes.
Could there be life floating high in the atmosphere of Venus where conditions are, at least, not so bad? What an exciting idea!
But this is science. Later reports in Nature were unable to reproduce the discovery using the same data from the giant €2 billion Atacama Large Millimeter Array (ALMA) radio telescope in Chile. Then, on 17 July this year, at the Royal Astronomical Society meeting in the UK, one team presented stronger proof that Phosphine is present in the clouds of Venus, and another team showed the presence of ammonia, which is also possibly an indicator of life. These so-called “bio-signatures” are not yet proof of extra-terrestrial life on Venus, so the debate and the work continue.
One of the Xhosa traditional names for Venus as an evening star is “Madingeni”. Idinga means an appointment, and Madingeni was code in the old days for secret meetings under “the kissing star” at a time when young people could not publicly date.
So, enjoy the beauty of Venus in our evening sky now through February. Maybe even arrange your own indinga to share viewing this brightest object in the sky (after the Sun and Moon).
- This article was first published in Talk of the Town, August 22, 2024. The newspaper serving the communities of Ndlambe and the Sunshine Coast, with a weekly wrap of Makhanda news, is available at stores from early on Thursdays. Donald Kurtz is Extraordinary Professor at North-West University in Mahikeng. He has an A-1 rating from the South African National Research Foundation, its highest rating. He also holds appointments in the UK of Emeritus Professor at the University of Central Lancashire and Visiting Professor of Astrophysics at the University of Lincoln. He was previously Professor of Astronomy at the University of Cape Town, where he worked for 24 years. Don has over 500 professional publications and was awarded the 2022 Service Award of the Royal Astronomical Society for a lifetime of public outreach and for his service on many international committees. He and his wife, who is originally from Grahamstown, now live in Port Alfred.
