Distant Exoplanet Shows Signs of Water Vapor And Earth-like Skies
Pulling together the greatest resources in the world such as the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope and the Kepler Space Telescope, one team of international astronomers caught the break they were looking for when they discovered clear skies and more importantly water vapor on a planet 122 light years outside of our very own solar system.
Publishing their results in this week's issue of the journal Nature, the researchers found that the planet HAT-P-11b is much like Earth in that it contains water vapor in a cloudy atmosphere surrounding the giant planet's surface. But the discovery of the microscopic molecules from distances so far away were as much attributed to luck as calculated detection, as the scientists happened to observe the planet on a day of "clear skies".
"When astronomers go observing at night with telescopes, they say 'clear skies' to mean good luck" lead author of the study published in Nature, Jonathan Fraine says. "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."
Though the discovery of water is a much-needed sign of hope for astronomers, who in recent years have been concerned that their efforts to study chemical compositions of exoplanets' atmospheres may be hindered, HAT-P-11b is far from the ideal specimen as a replicate of Earth. Neptune-like in appearances, the planet that lies in the distant Cygnus constellation (the Swan) is nearly 5 times larger than Earth in size. And as it is only 5 million miles away from its parent star, versus the Earth's 93 million mile distance from the sun, the planet's surface temperature is above 1,100oF and its year is less than five days long.
Looking past the cloudy outer atmosphere, the team was able to analyze trace fragments of starlight to accurately identify distinct signatures of water molecules using the Hubble's Wide Field Camera 3 and an imaging technique known as transmission spectroscopy. Finding a night of clear skies, the nearby starlight was able to radiate through the planet's outer atmosphere and reveal the water vapor within.
"We set out to look at the atmosphere of HAT-P-11b without knowing if its weather would be cloudy or not" co-author from the University of Cambridge, Nikku Madhusudhan says. "By using transmission spectroscopy, we could use Hubbble to detect water vapor in the planet."
"This told us that the planet didn't have thick clouds blocking the view and is a very hopeful sign that we can find and analyze more cloudless, smaller, planets in the future. It is groundbreaking!"