On November 3, 2020, an international team of researchers revealed the existence of a planet that defies imagination. K2-141b, this Earth-sized exoplanet—about 202 light-years away in the constellation Aquarius—offers a glimpse into an environment far more extreme than any in our solar system. This otherworldly planet is a study in contrast, with one side covered in scorching magma oceans and the other frozen in perpetual darkness.
A Planet of Extremes
K2-141b orbits its star at a blistering pace, far closer than even Mercury is to our sun. This proximity results in a planet that is tidally locked, meaning the same side always faces its star. As a result, about two-thirds of the planet is bathed in perpetual daylight, while the remaining third is locked in eternal night. The temperature difference between these two hemispheres is staggering. The star-facing side reaches an estimated 5,700 degrees Fahrenheit (3,000 degrees Celsius), hot enough to vaporize rocks, while the night side plunges to a frigid -330 degrees Fahrenheit (-200 degrees Celsius).
Magma Oceans and Rock Vapor Atmospheres
One of the most striking features of K2-141b is its magma ocean, which is believed to be about 62 miles (100 kilometres) deep. This ocean of molten rock gives rise to a thin atmosphere composed of vaporized minerals, including sodium, silicon monoxide, and silicon dioxide. The extreme heat on the day side causes these minerals to evaporate, creating a rock vapour atmosphere that is then carried by supersonic winds to the planet’s cold, dark side.
Here, reminiscent of Earth’s water cycle, the vaporized minerals cool and precipitate back to the surface as rocky rain. The mineral-laden winds then return to the magma ocean, where the cycle begins anew. However, this process is far less stable than Earth’s water cycle, and scientists believe that the mineral composition of K2-141b’s surface and atmosphere will gradually change over time.
Insights into Planetary Evolution
K2-141b is more than just a curiosity; it offers scientists a rare glimpse into a stage of planetary evolution that our own Earth went through billions of years ago. Back then, Earth and other rocky planets in our solar system were molten worlds with magma oceans and extreme conditions similar to those on K2-141b. As these planets cooled, they solidified into the rocky worlds we know today.
York University’s Tue Giang Nguyen, lead author of the study published in the Monthly Notices of the Royal Astronomical Society, notes that K2-141b’s unique features provide a window into the processes that shape planetary evolution. With the help of next-generation telescopes like the James Webb Space Telescope, scientists hope to gather more detailed data on K2-141b’s atmosphere and surface conditions, further unravelling the mysteries of this hellish world.
A Glimpse of the Universe’s Extremes
While planets like K2-141b may seem alien and inhospitable, they are crucial to understanding how planets form and evolve. The extreme conditions on K2-141b push the boundaries of what we know about planetary science, offering a vivid reminder of the incredible diversity of worlds that exist beyond our solar system.
As scientists continue to study K2-141b, they may uncover more secrets about how planets like Earth transitioned from molten lava worlds to the habitable environments we depend on today. For now, K2-141b stands as a testament to the universe’s capacity for both wonder and extremes.
Bottom Line: K2-141b is an extraordinary exoplanet with magma oceans, a rock vapour atmosphere, and supersonic winds, offering valuable insights into the early stages of planetary evolution.
Source: Modelling the Atmosphere of Lava Planet K2-141b: Implications for Low- and High-Resolution Spectroscopy via McGill University.
