In a groundbreaking discovery, NASA's Hubble Space Telescope has detected the presence of water in the atmosphere of GJ 9827D, a distant exoplanet. With a diameter roughly twice that of Earth, GJ 9827D is considered the smallest planet of its kind to reveal such a finding. Located approximately 97 light years away, the tiny exoplanet orbits a red dwarf star, completing one revolution in just over six Earth days.

Led by Laura Kreidberg from the Max Planck Institute for Astronomy in Heidelberg, Germany, the research team has described the discovery as "a landmark" in the field of astronomy. This finding brings scientists closer to characterizing truly Earth-like worlds.

The observation of water on GJ 9827D was made possible through atmospheric detection using the Hubble telescope. This marks the first time that such an exoplanet has been discovered to exist around other stars. Björn Benneke, an astronomer from the University of Montreal's Trottier Institute for Research on Exoplanets, believes that this is an important step towards understanding the prevalence and diversity of atmospheres on rocky planets.

Over a period of three years, Hubble observed GJ 9827D during eleven transits in front of its host star. By filtering the light produced by the star through the exoplanet's atmosphere, astronomers were able to observe key spectra that indicated the presence of water molecules. However, it is still unclear if the planet is primarily a "water world" or if the detected water vapor is found in its hydrogen-rich atmosphere.

Despite possessing water like Earth, GJ 9827D's close proximity to its star has led to extreme heat, with temperatures reaching up to 800 degrees Fahrenheit. This makes it unlikely that the planet could support life, especially if there is an abundance of water vapor in its atmosphere.

Pierre-Alexis Roy, the lead author of the study, suggests two possible scenarios. If GJ 9827D has an atmosphere rich in hydrogen with a small amount of water vapor, it could resemble a mini-Neptune or Jupiter's moon Europa, which contains twice as much water as Earth. Alternatively, the water vapor may exist above the exoplanet's rocky body, indicating that GJ 9827D has equal parts water and rock.

The discovery of water on GJ 9827D is seen as a gateway to future investigations. Thomas Greene, an astrophysicist at NASA's Ames Research Center, highlights the potential of NASA's upcoming James Webb Space Telescope (JWST) to reveal more about the planet. The JWST's infrared observations may uncover additional information about the planet's composition, including carbon-bearing molecules like carbon monoxide, carbon dioxide, and methane. This data will aid in understanding how GJ 9827D was formed.

The team's findings, published in The Astrophysical Journal Letters, have deepened our knowledge of exoplanets and opened up new possibilities for extraterrestrial exploration. With the discovery of water on GJ 9827D, scientists are closer than ever to understanding the nature and characteristics of distant worlds beyond our solar system.