Signs of Water Discovered on Distant Planet

Scientists have recently found the traces of water in starlight filtered through the atmosphere of a giant gas planet outside our solar system. This is the first solid evidence of another planet, outside our Solar System to possess water, the crucial ingredient for life to develop. This finding is detailed in the July 11^th issue of the Journal Nature.

The planet, called HD 189733b, belongs to class of gas giants called "Hot Jupiters" which orbit their stars at a distance closer than mercury is to the sun (less then 36 million miles). The hell-like world is about 15 percent bigger than Jupiter and orbits a sun-like star located 64 light-years away in the constellation of Velpucula, the Fox. It has an average temperature of 1,340 degrees Fahrenheit (727 degrees Celsius) and zips around its star in just two days.

Astronomers hypothesized that unlike Earth, where the atmospheric temperature cools with altitude, the temperature of HD 189733b's atmosphere is uniform over a range of altitudes.

Scientists had previously searched for signs of water on HD 189733b but failed to find any. At the time, they suspected the water might be hidden beneath a thick layer of dusty, metal like clouds.

In a previous study, using the Hubble space telescope, scientists looked for spectral absorption lines created by radiation traveling up from the interior of the planet. That radiation then passes through layers of cool gas that selectively absorb certain wavelengths of light. Without a temperature difference, no absorption occurs.

"The detection comes as a relief for theorists who had predicted that water vapor should be a significant component of the atmospheres of hot Jupiter's," Knutson wrote in a related Nature article.

This find is credited to the Nasa Spitzer Space Telescope, a gigantic orbiting observatory. Using Spitzer's infrared camera, the Nasa team used Spectroscopy, a technique that analyzes light that is emitted from the interior of the parent star and which passed through the planet's atmosphere on its way to Earth. The absorption of gas occurs because of the temperature difference that exists between the star's atmosphere and that of the planet.

The researchers found that the planet absorbed starlight in such a way that could only be explained by the presence of water vapor in its atmosphere.

Although water is an essential ingredient for life on Earth, HD 189733b and other hot Jupiters are unlikely to harbor any creatures due to their close proximity to their stars. Water vapor does exist in other parts of the universe. If it can exist in raging infernos, trillions of miles away, it likely exists in many other places.

http://www.nature.com/nature/journal/v448/n7150/full/448143a.html