The quest to find signs of life in another planet gets a new boost with the discovery of a Neptune-size planet located beyond the solar system having traces of water vapor in its atmosphere.
In a new study published in the journal Nature on Sept. 24, astronomers examined the atmosphere of the planet called HAT-P-11b, an exoplanet that orbits a star different from the solar system's sun. The investigation used NASA's space telescopes and a technique known as transmission spectroscopy, which observes the planet as it passes in front of its parent star HAT-P-11. The study revealed that the planet, which is located 124 light years away from the Earth, had water vapor in its atmosphere.
"We detected water vapor absorption at a wavelength of 1.4 micrometres," writes Jonathan Fraine and colleagues from the department of astronomy at the University of Maryland. "The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e)."
The astronomers also observed that HAT-P-11b has clear skies; the atmosphere is free of clouds that could block the view, allowing scientists to deduce the amount of rock and ice in the planet's interior and indicating the possibility that more cloudless planets may be discovered and studied in the future.
"When astronomers go observing at night with telescopes, they say 'clear skies' to mean good luck," said Fraine. "In this case, we found clear skies on a distant planet. That's lucky for us because it means clouds didn't block our view of water molecules."
The discovery marks the first time that water has been discovered on a planet smaller than Jupiter. Using the U.S. space agency's Hubble, Spitzer and Kepler space telescopes, astronomers found that the exoplanet is blanketed in hydrogen gas, water vapor and other molecules that still need to be identified.
Astronomers have long been looking for evidence that life exists in other parts of the universe and the discovery certainly gave this quest a boost. The researchers also hope that the findings could pave the way to better understanding how planets, including the Earth, came to exist.
"If we can detect water, methane, carbon monoxide, carbon dioxide, etc., in dozens to hundreds of exoplanet atmospheres of various bulk properties, then we will be able to paint a much clearer picture of how planets form, and, likewise, how Earth formed," Fraine said.
