How can a rocky planet be close to its star, but also preserve water and life on its surface? A new study of a recently discovered exoplanet offers a key to solving this mystery, which will make it possible to understand why life on Venus did not evolve like it did on Earth.
This exoplanet is very close to its star, but it still seems that the conditions for the evolution of life on its surface are still possible, according to a three-dimensional simulation conducted recently by researchers and published in the journal Monthly Notices of the Royal Astronomical Society: Letters.
High heat on Venus may have caused water to evaporate under the influence of global warming (Getty Images)
The earth and Venus are the same but different. Why?
Until recently, Venus was considered a potential twin of our planet, two adjacent to the solar system and orbiting relatively close around the sun, and with similar sizes and densities.
But the first probes that man walked to the neighboring planet starting in the sixties of the last century showed that the conditions that prevail in it are radically different: the atmospheric pressure on Venus is about 92 times higher than on Earth, the temperature on its surface reaches 475 degrees Celsius, and the planet is covered with a dense layer of sulfuric acid clouds, according to the Institute of Astrophysics in Andalusia.
However, scientists believe that Earth and Venus had similar childhood with volcanic activity that released gases and shaped the atmosphere, and possibly also liquid water, but the high heat on Venus may have caused the water to completely evaporate under the influence of runaway global warming, which created the extreme conditions that exist today.
To understand this difference between Earth and Venus, researchers are studying rocky, Earth-like exoplanets that exist in the so-called "habitable zone" around their central star.
It is the region around the star where planets can receive the ideal amount of heat to maintain liquid water on their surfaces. But researchers have discovered unexpected environments in outer space that could sustain life.
Imaginary image of LP 890-9C with its red dwarf star (NASA)
One such unexpected environment is a planetary system discovered by the Birmingham Telescope in September last year orbiting LP 890-9, about 890 light-years away. This planetary system consists of two rocky planets that are relatively small but about 9 percent larger than Earth and orbit in orbits very close to the center star known as a weak-glowing red dwarf.
The planet farther away, dubbed LP 890-9c, only takes 890.9 days to complete a full orbit around the star, the same length as it orbits itself, meaning half of it is illuminated all the time and half is immersed in complete darkness and does not reach the light.
The researchers found that the planet receives 91 percent of the solar radiation reaching Earth, placing it on the inner edge of the habitable zone around its star. But it's very close to the region where the wild greenhouse effect occurs, so they think its atmosphere may be very similar to that of Venus.
Between the warm earth and the barren flower
To explore how the planet's atmosphere evolved, astronomers have created three-dimensional models of the composition of the planet's atmosphere based on a number of variables such as the planet's size, mass, chemical composition of the atmosphere, surface temperature, pressure, thickness of the atmosphere and cloud cover.
These three-dimensional models make it possible to calculate the radiation emitted by the planet in certain regions of the electromagnetic spectrum, thus knowing the chemical composition of the atmosphere.
An imaginary image of the evolution of LB890-9c's atmosphere between an Earth-like and a Venus-like climate (Cornell University)
The simulation included several scenarios that reflect the evolution of rocky planets, from a warm Earth-like planet where life is still possible, to a barren Venus-like planet with a carbon dioxide-rich atmosphere.
The results showed that the planet's fate looks significantly different depending on whether it has warm oceans, a steamy atmosphere, or if it has lost its water, assuming it had oceans like Earth.
According to the researchers, the likeness of this planet to Venus makes it an ideal laboratory for studying the evolution of the atmosphere of Earth-like planets and explaining the climatic difference we observe between Earth and Venus.
These scenarios could provide important new insights into how quickly Earth-like planets lose water, about the evolution of rocky planets on the inner edge of the habitable zone, and about the future evolution of our planet.
According to the simulation results, the oceans on Earth are expected to evaporate billions of years from now when the sun turns into a red giant, and its atmosphere will fill with steam before it reaches the boiling stage.