Posted by ESA’s upcoming PLATO mission could significantly expand the known population of rocky planets that resemble Venus rather than Earth, helping scientists better understand why terrestrial planets can follow dramatically different climate paths. Combined with Solar System missions studying Venus, including DAVINCI and VERITAS, PLATO’s findings could help reveal how often Earth-like planets become Venus-like worlds instead.
PLATO, short for PLAnetary Transits and Oscillations of stars, is scheduled for launch in 2027. Although one of its major goals is to find potentially habitable rocky planets around Sun-like stars and red dwarfs, the mission will also search for planets inside the so-called Venus Zone. The Venus Zone lies inward of the habitable zone, where planets receive enough stellar radiation to potentially trigger a runaway greenhouse effect. Its outer boundary marks the point where such a greenhouse could begin, while the inner boundary corresponds to irradiation strong enough to strip away a planet’s atmosphere.
A new study led by planetary astrophysicist Stephen Kane estimates that PLATO could detect roughly 170–280 terrestrial planets in the Venus Zone with radii between 0.8 and 2 Earth radii. Under more conservative assumptions, around 40–80 of these could be approximately Earth-sized.
A particularly valuable subset will orbit brighter stars. Researchers expect PLATO to find about 50–85 terrestrial Venus Zone planets in this sample, including approximately 13–22 Earth-sized worlds. Their bright host stars should make it easier to measure planetary masses through radial-velocity observations, determine stellar ages using asteroseismology, and perform future atmospheric studies.
These discoveries could address a fundamental question in planetary science: is Earth’s stable, temperate climate common, or unusually rare? Venus and Earth have similar sizes, masses, densities, and bulk compositions, yet their climates evolved in radically different directions. By building a much larger sample of “exoVenuses,” astronomers can compare planetary environments and better constrain where runaway greenhouse conditions begin.
For more details, read the full article by Universe Today.
