Eric Warner Staff Writer
On Sept. 11, 2019, astronomers from the University College London released their findings about a new habitable planet in a research study titled, “Water Vapor on the Habitable-Zone Exoplanet K2-18b”.
The planet K2-18b was first discovered in 2015, during the K2 Mission of NASA’s Kepler Telescope using a process known as the Transit Method. This method essentially works by having the telescope observe a particular star, in this case, a red dwarf star, which detects for shadows that move over the its surface. The shadows are indications of planets moving within the star’s orbit, much like how we may see Venus or Mercury block parts of the sun in the Solar System. The telescope instantly detects any dips in the star’s brightness when a planet transits the star, hence, the method’s name. The planet’s size can then be calculated by measuring how long it takes for the planet to orbit once around the star, determining how much the brightness of a star drops, and measures the exact size of the star itself. Once the planet’s size and the star’s temperature are measured, the planet’s temperature can be found, which would then determine whether the planet is habitable. K2-18b is one such planet, located in its system’s Goldilocks zone where its temperature is not too cold nor too hot to potentially support earth-like life.
The astronomers then took this data to the Hubble Space Telescope where they continued to observe the planet in eight more transits and have, thus, detected signs of water vapor, liquid water clouds, and potentially rain in K2-18b’s atmosphere. Earth and K2-18b receive about the same amount of radiation from their stars , making it very plausible to host liquid water clouds.
Nonetheless, it’s still relatively unknown what kind of surface K2-18b is home to. It’s a very dense planet, similar to the density of Mars. Many astronomers expect it to have a similar surface to Mars despite K2-18b having water in its atmosphere.
Since K2-18b is located 110 light-years away, astronomers are limited to what degree they can learn about this exoplanet. Nevertheless, the mere discovery of water on another planet far from the Solar System is universally exciting as Professor Björn Benneke, the lead author of the astronomers findings, stated, “This represents the biggest step yet taken towards our ultimate goal of finding life on other planets, of proving that we are not alone.”
K2-18b will continue to be the subject of further studies once the James Webb Space Telescope is operational. This telescope, which is expected to launch in 2021 onto its 30-day million-mile journey, is the successor to the universally changing Hubble Space Telescope. Webb will serve thousands of astronomers worldwide as it studies “[…]every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.” This telescope will be able to effectively travel back in time using infrared technology to observe the cosmos from 100-250 million years ago, seeing when the first stars and galaxies were forming in the young universe. By the time the light of these celestial bodies from millions of years ago reaches the Solar System, its wavelength would have shifted to towards the color red, hence the use of infrared technology.
Webb will also be able to study the atmosphere of exoplanets, such as K2-18b, to a much more detailed degree through a process called spectroscopy which is the science of measuring light at different wavelengths. With this ability, Webb would be able to capture spotty images of K2-18b’s color, weather, vegetation, oceans, and, hopefully, sentient life.