Introduction
Earth is a unique planet in the Solar System as the only one known to support an active life. However, scientists are constantly in the search of other life in the universe. Other planets in our vicinity may offer clues, with Venus and Mars potentially once having supported life.
Earth, Venus and Mars
Venus is currently one of the most inhospitable planets to life, with average surface temperatures reaching as high as 900 degrees Fahrenheit. However, researchers believe that 2 to 3 billion years ago, it had a habitable environment with the potential for liquid water. An event nearly 700 million years the atmosphere was dense and extremely hot. The planet is believed to have had a surface and climate similar to Earth, capable of supporting life. In 1978, NASA found evidence of shallow oceans. Since then, modern simulations by NASA’s Goddard Institute have shown that Venus would have been able to maintain stable temperatures and climate, depending on the level of water coverage, but in virtually every scenario, capable of preserving life. Furthermore, the topography of Venus, both as it is today or more similar to Earth’s, in combination with atmospheric compositions 4.2 billion years ago, was able to sustain life at temperatures ranging between 68–122-degree Fahrenheit for approximately 3 billion years (Mathewson, 2019). Unfortunately, today it is difficult to potentially recover any physical or biological evidence from the planet’s surface because of such hazardous conditions and tremendous solar radiation that is present there.
Meanwhile, Mars has a much milder climate. Mars only had an atmosphere only for a short period after formation, which was eroded by solar win due to a lack of magnetic field protection. In 2004, a NASA rover found overwhelming evidence that Mars once had flowing water. This has since been supported multiple times, with scientists believing that the Elysium Plains, a well-known region among the equator was a frozen ocean at some point. Scientists also discovered other clues such as the presence of methane in the atmosphere, with some seasonal variations, indicating a potential for microorganisms, but can also stem from geology (Drake, 2022). As of the current day, no definitive proof of life has been found on Mars, only assumptions that habitable conditions of the past and some samples suggest that some form of microorganism life had or continues to exist.
Conclusion
Overall, both planets have had unique past geology, indicating the presence of atmosphere and life-supporting conditions. However, evidence at this time is circumstantial and based on assumptions. Potentially these planets supported life but it is not confirmed.
References
Drake, N. (2022). Why signs of life on Mars remain so mysterious. National Geographic.
Mathewson, S. (2019). Venus may have supported life billions of years ago. Space.com.